# How to secretly harvest/farm human beings as a primary food supply?

A group of individuals from a technologically advanced alien race have been found to be intellectual dissidents by their peers and exiled to Earth as a consequence.

Earth was selected as the location of their sentence as it happens to be hospitable for their species and the convicts have been given some technologies (detailed below) to help them make a new life for themselves on earth.

These aliens are not humanoid. They cannot disguise themselves as people. Furthermore they do not want to reveal themselves to humanity at large, thus they must stay hidden from the general population. They are however willing, if not terribly keen, on interacting with small groups (such as government officials) as long as they believe their existance will not be divulged publically.

The aliens are essentially entirely carnivorous and the entire group requires about 60,000 kilograms of meat to sustain itself per day. They were not given technologies to synthesize artificial meat, nor were they given herds of animals to farm. Furthermore because of certain ethical and cultural considerations, they wish to live in harmony with their habitat and thus they greatly prefer to kill/farm/consume species which they deem as "invasive/"unchecked", species which are causing untold havoc to the ecosystem. This (unfortunately for us) happens to be, according to them, humans.

So the question remains, how will this group of aliens harvest and ship 60,000 kilograms of human meat (when you account for all the non-meat part of humans beings that adds up to about 2000 individuals, by the way) per day to the hidden central location where they all live?

• They have settled in a large underground cavern which they themselves created located in Nevada, USA.

• The technologies they possess include advanced computers capable of translating mostly accurately any human language, hacking any website/online service with low to medium level security and running calculations dozens of times faster than Earth super-computers.

• In addition they have extremely advanced batteries which should be able to fuel their small-society for centuries and the ability to manufacture dozens of androids which can be customised to exactly copy the likeness/speech of any human and which possess the software needed to engage in basic inter-personal interactions.

• They can create bioweapons and artificial viruses.

• The aliens have rather extensive knowledge on physics (FTL travel, wormhole creation) and engineering (fusion reactors, robotics).

• They would prefer to eat healthy human beings (no eating sick or elderly if at all possible; extra credit to answers which do not require them to do so).

• These aliens have no qualms with majorly distorting the status quo. They can use their influence to topple governments, inflict worldwide/nationwide plagues, etc...

• Comments are not for extended discussion; this conversation has been moved to chat. – Tim B Aug 9 '17 at 21:11

I'm going to go with "can't be done." 2,000 people a day (I'm assuming adults based on your offered statistics) or 730,000 people a year would be beyond noticable, even if you're harvesting planet-wide. Approximately 55 million people die each year (source). You're talking about one out of every 75 people. The collaborating government would need to come up with some way to convince people the deaths were natural, the cremations were expected, and that the lack of a body between last-breath and first-flame wasn't a big deal. Facebook would be glowing hot with conspiracy theories within a month.

As mentioned in your comments, corpses might be a solution... but we're back to swapping them out somehow. The consipiracy would be enormous --- and it's difficult to believe.

Sorry, mate. But while people may come up with some clever ideas, you need to seriously reduce that number for any of them to be believable. It would be easier to explain the dissapearance of 200 winos a day by colluding with the city governments of some big cities than 2000 people generally. Unfortunately, there aren't enough winos and homeless people for that number to not be noticed very quickly.

EDIT: I'm not even going to go with 200 winos — because even that is per-day. If you spread it out among the 100 largest cities in the world, maybe... but now you're talking about a massive shipping conspiracy to get the people to the dinner table.

Having said this. Take the time to look into how the Nazis were shipping and killing the Jews during WWII. It's a morbid subject and an utterly distasteful (if not downright insulting) reason to use the historical context, but it's the closest you'll get to the complexities of genocidal behavior. And at the quantities you're proposing, it's genocidal behavior.

EDIT: A coment by @Ando-Jurai suggests a solution. Given that our enterprising aliens have a decent storage technology, they could periodically manipulate the world to war to hide harvesting. If they have the ability to generate earthquakes, they could do the same. I'm still worried about the numbers involved. You'd have to devestate very high populated areas to hide the take. But, maybe...

• sigh I suppose this may indeed simply be impossible. I still find it rather surprising that with all that advanced technology they can't manage this. Still I might point out that they don't actually care whether people realize something huge is going on or not, they just don't want people to know it's their doing. Perhaps that clarification helps...? Probably not. – AngelPray Jul 31 '17 at 7:25
• Nope. The problem isn't their advanced technology. The problem is our technology. Today we notice the smallest injustice within seconds, pitch it to all our friends within minutes, and it becomes a viral Internet meme within hours. I just don't know how long the aliens can keep their dinner plans secret when the whole world is demanding answers of their governments. Even a fake plague would only buy you time. And not much, at that. – JBH Jul 31 '17 at 7:28
• Now we're cooking! If the public was sold on the idea that they couldn't have access to the bodies for, e.g., burial, then it's possible. But a natural public yearns for solutions. It's something that wouldn't go on forever without some kind of "we really can't solve this" solution. Remember, you'd have every biologist on the planet trying to solve the problem. – JBH Jul 31 '17 at 7:37
• And then you have tons of national and international health agencies (public and private) fighting the real plague. They're going to want to dispose of the corpses themselves, so if you want to ship them to Nevada you're increasing the number of people who will have to join your conspiracy. And for some reason public health people are often anti-genocide. – MissMonicaE Jul 31 '17 at 14:15
• "Today we notice the smallest injustice within seconds, pitch it to all our friends within minutes, and it becomes a viral Internet meme within hours." Much of what is said is highly accurate -- provided you are in a region people care about. If the location is instead controlled by gangs/mob/local warlords or is terribly underdeveloped and impoverished, folks rarely take notice. In fact, if you were to offer the right gifts to the right warlords, they might take care of everything for you. Foment a little superstition and fear, and you've got a servant colony. – Pyrotrain Jul 31 '17 at 18:33

These aliens would not foment chaos and war. What they want is large numbers of humans having large numbers of babies, eating well, living through reproductive age and long enough to help with the rearing of grandchildren, with the main reason for non accidental mortality being the harvest of the aged for meat. The aliens would therefore use their tech and act behind the scenes to

1: Promote sustainable intensive agriculture. This means irrigation, erosion control, synthetic fertilizer, aquaculture.

2: Promote vegetarianism. It is a more efficient use of land resources.

3: Promote peace. War causes disruption, decreases agricultural output, increases mortality rates, and reduces available humans (and their meatiness).

4: Eradicate disease. This means mass vaccinations, clean water, safe childbirth, effective medicines.

5: Encourage large families. One way to do this is to keep people agrarian with a need for much man / woman power.

6: Promote obesity. The obese have more caloric value. Interestingly, some vegetarian populations ( I am thinking of Indians) do have a tendency to be large - it is possible that a high carbohydrate diet can push metabolism that way. The aliens might also alter the human fecal biome to this end.

6: Harvest. Ideally this would not be some surprise to the people involved - that again makes fear and chaos. It would an orderly end of life. In the Burroughs Mars books, old people voluntarily take a trip down the river to the promised land (where, as it turns, out they are eaten by apes) but the process is voluntary. Similarly in Soylent Green, tired old people report to recycling centers for a peaceable death (and, it turns out... well, watch the movie you youngsters. It is good).

All in all having people lead a productive, full bellied, disease free life with their large families and check out at age 60 to become food seems like a pretty decent trade: certainly a better quality of life for a large proportion of the populace who today live hungry, scared and sick.

We would not be farmed. We would be tended.

• Started thinking of Logans Run with your 6.2 point on Harvesting. – Darren Bartrup-Cook Jul 31 '17 at 14:57
• Promote vegetarianism; "I prefer corn-fed Iowa." – Hydraxan14 Jul 31 '17 at 17:05
• Whether vegetarianism uses land more efficiently depends a lot on the land in question. There's lots of land that won't grow plants which are directly consumable by humans with any reasonable amount of effort, but which can provide food for dedicated herbivores. Also there are a number of human genetic lines which develop health problems on a vegetarian diet, including some (particularly in the far north) which are close to becoming obligate carnivores. – Perkins Jul 31 '17 at 18:59
• @Thucydides Huh? What's wrong with free range meat? The aliens would love to eat well-fed, happy, free range humans. And I dare say most people would probably not like to be kept in tiny animal pens either. Win-win for everybody. – AngelPray Aug 1 '17 at 2:32
• Free range farms (I know a few free range farmers) don't have anywhere near the productivity as "factory" farms in terms of meat, egg or milk output (I would imagine the same applies to other farm animals as well). Aliens may prefer the taste of Free Range humans, but much like Free range produce, it will be rare and expensive compared to "factory farmed" humans. – Thucydides Aug 1 '17 at 2:35

A new company LifeStore Inc. has taken up the challenge of harvesting flesh at an early age and storing it for use in later life medical care as needed.

The game is up if you don't actually offer the promised improved health care, but such a thing should not be a problem for the ETs (BTW, be sure to pronounce ETs as eaties).

Surprisingly, (and most convenient), it turns out that the necessary amount to be harvested is 0.25 kilograms of mostly muscle preferable at age 16 (including choice meat cuts). While this amount is quite a bit and requires some recovery time after the muscle is removed, you recover full function in relatively short order. Since over 100 million people reach age 16 each year, you can harvest over 25 million kg per year, which is equal to about 68,500 kg/day. All the meat the ETs want with spare capacity. You even have a variety of cuts; well-marbled Americans may be a popular choice. Even low-tech humans could do this minor surgery and freeze the product for shipping to Nevada. This is not a problem in 3rd-world countries if you supply the liquid nitrogen and make some basic medical supplies available for free at the LifeStore clinics. LifeStore would also make life-saving tech available for these 3rd world nations for humanitarian reasons (well, an ET meat supply reason at least)

Initial harvest can actually take place at up to age 60, though the results are not as good, and would be considered worthless if you already contracted the disease you are trying to fix (to preserve the illusion of harvesting being necessary). This also allows for quick build of the initial inventory, though the quality is not as prime as that harvested at age 16.

If you fail to submit to harvesting, you will not be able to get the new advanced health care options for treating cancer, heart disease, etc., and since LifeStore inc, plans for the long term, there is no charge for the initial harvesting (to maximize compliance). Social conventions will take care of the slow adopters (You mean you would let your kids die because you would not allow the harvest?) There would be pro-harvest movies, music and television of course.

Of course, cheaper cuts for lab-grown human flesh would certainly be available, but all ETs will much prefer the natural meat, because otherwise they would simply do this themselves.

This would be non-disruptive to humans except for the effects of things like curing cancer, and supplies all of the meat for the ETs without revealing their presence. A false front that looks like a real medical center for all of the goodies would satisfy skeptics when the medical miracles happen as promised. Note that the medical benefits do not actually have to depend on using the samples at all.

If you doubt muscle can be regrown, we have already done it, and you can bet that the ETs could do it better.

@Veehot does raise the issue of regulatory compliance and the fact that the fraud of the Harvest will be identified as such, an oversight on my part. I do not doubt that this would be an issue in the early years, but when other countries allow LifeStore to cure cancer, strokes, heart-attacks, etc. that are otherwise hopeless, I have no doubt the regulatory agencies will fail to discourage the public demand for LifeStore, and governments will respond in kind -- otherwise riots and medical tourism will prevail until the government concedes. Consider the case of saccharine, the FDA was on the path the regulate it out of existence, but due to public outcry, they eventually settled on just a warning on the label. On a similar note, I see that the US congress is still toying with allowing incandescent light bulbs, even now that LED bulbs are a great replacement in most cases.

Scientists that insist there is no medical need for Harvesting will be ignored as long as the cures are real. The social pressure to allow LifeStore to do exactly as they plan will override all obstacles in fairly short order once the cures are recognized as the real deal.

• This is good. But be aware that human scientists may state that there's no need for meat samples for curing cancer. For the company to work as intended withouth raising suspicions, it would need to pass regulations, which may include disclousure of the technology used for curing cancer. Of course it would be under a patent, but the technology should be publicy available, which may expose the hidden truth. – Veehmot Aug 1 '17 at 19:55
• @Veehmot, when LifeStore cures the cancers that others do not, who is going to complain about harvesting a muscle sample, regardless of what some scientists say. And, no, I would not patent it, I would keep it as a trade secret. If the US FDA does not want to allow this, let them try to overrule the American public that wants their cancer cured. It would be unanimous in Congress once they figure it out. – Gary Walker Aug 1 '17 at 20:09

North Korea

Don't settle in the US, settle in the most totalitarian corner of the globe.

While I'm pretty sure that North Korean people would notice that many people missing, what exactly are they going to do about it? Who can they complain to, who can they ask questions of? If the aliens control the government, any indication that you think something's wrong will just get you shipped off to the farm as well.

The same total lack of free communications will also mean that a lot of the defectors out of North Korea would simply not be aware of the problem, and those that do might not initially be believed. And even if the rest of the world starts suspecting there's something quite wrong, what can they really do? Maaaaaybe they can get some spies there and find out the truth, but in the current state of nuclear affairs, an invasion is out of the question.

• I think this might be the right vein to follow. Instead of harvesting from major players, take advantage of difficult political situations to hide your activities. North Korea, third-world warring states, mobs, terrorists... basically anyone who would be willing to exchange victims for weapons/energy/technology. Just tell them to deliver their "offerings" to X location, wormhole them away, and deliver a box of weapons. Use an android or even an anonymous online presence as a front-man. Use fear/superstition to enforce silence. – Pyrotrain Jul 31 '17 at 15:34
• North Koreans (with one obvious exception) tend to have very little meat on their bones... – AngelPray Jul 31 '17 at 17:51
• @AngelPray nothing says you can't feed them up after you get them. – Ben Barden Jul 31 '17 at 20:32
• Population of North Korea is about 25 million. May not be enough to support a harvest 730K people per year. Since they are a little small on the average, would need more than 730K per year too. – Gary Walker Aug 1 '17 at 11:59
• @GaryWalker It'll be enough for about 30 years, enough time to come up with a different solution – PJvG Aug 2 '17 at 11:32

## Open a funeral home

Or, more realistically, a chain of them. More than enough people die on a daily basis from accidents or from causes that don't significantly damage the body, like heart attacks or strokes. All that your aliens need to do is to harvest meat from humans that have already died of suitable causes, and then cremate the rest of the remains.

Close to a million people die of heart disease, accidents, or strokes in a given year in the US alone. Around 150k of those are accidents, so if the other causes aren't acceptable for the aliens, they'll have to incorporate some foreign countries, as well. About half of those people are cremated.

Cremations offer the best chance at covertly harvesting humans as food. They're done out of sight of the general populace, and most people don't really have a good idea of how much ash they should produce. Muscle comprises 30-40% of a person's weight, so most people probably wouldn't realize that their loved ones were butchered at the funeral home. Unlike something like thousands of people going missing, nobody would notice a trend in significantly reduced cremation rates, especially if the aliens doctor national databases (if those exist) to hide that trend.

This would work better in a country like China, of course, due to its higher population and higher cremation rate.

## Encourage drug consumption

If the aliens need more humans to die from accidents, this is the easiest way to do it. Use wormhole technology and advanced science to produce and distribute drugs. The spike in deaths from both accidents and overdose will be noticed, of course, as will the rising crime rates, but people will blame those things on moral decay, not on aliens. Meanwhile, all of those bodies will head to the funeral homes for processing, ensuring a healthy food supply for hungry aliens.

• Do note that the little urn of ashes traditionally given to the family after cremation is actually not all of the ashes anyway. It would have to be a much larger urn to hold all of them. – Perkins Jul 31 '17 at 19:05
• The only issue, for lack of a better word, is freshness. Funeral homes typically get bodies hours after demise. The bodies they receive are intact and usually, have not been refrigerated. Hunters field-dress their kills (removal of all internal organs and blood) immediately. – Andrew Neely Jul 31 '17 at 20:52

JBH is right in pointing out that it would be noticeable. But who would notice, and what would they do about it?

• Rational and scientific-minded people would discount "anecdotal evidence" and look at the statistics. So one of the first steps of the aliens would be to discredit scientific inquiry. Make it acceptable or at least common to pick your own alternative facts. Make the majority distrust those "elites" who would come up with statistical evidence.
• The conspiracy would have to find someone or something to blame. Most "missing persons" are not dead after all, they just broke of communications. Find some talking heads who raise the problem of deadbeat dads who disappear rather than pay child support. Have the report peppered with anecdotal evidence (see above) rather than solid statistics. The report isn't there to convince serious journalists, the summary gets tweeted directly to the general population.
• The conspiracy could make large parts of the population fear the cops and other authorities, and encourage them not to file missing person reports. Have some illegal immigrants who inquire about missing persons arrested and deported, for instance.
• At the same time, make border protection ineffective so that more and more illegal immigrants come in through a "revolving door" -- they come, work for a couple of months, get deported, come back. This constant reshuffle erases traces.

Of course it would fail in the long run, but that's plot points for your story.

Follow-Up: As Yakk pointed out, we are talking about very large numbers. However, the number is roughly comparable to the annual illegal immigration into the US. Your fictional conspiracy controlling the US government and legislatures should be able to cause a five-fold increase in illegal immigration. And having one quarter of those disappear without much of trace would be difficult, but many citizens would be willing to ignore it.

• The required numbers would be considerably less than the population growth of South and Central America.
• Of course there would be observers who realize that lots of victims are disappearing. They would complain. They would be just one more group complaining about something, from vaccination to teaching evolution to climate change. Muddle the waters.
• Come up with regulations to encourage illegal immigrants to shuffle about. Perhaps strict (and strictly enforced) laws which require employers to check the residency status of their workers, unless they were hired from out-of-state for less than one week.
• 3/4 of a million is 1/75 of all deaths. Restrict it to a sub population and we are talking about a massive increase in death rate in that population. – Yakk Jul 31 '17 at 12:56
• Indeed, hiding facts from people is much harder, than getting them to ignore the facts alltogether. – Tomáš Zato - Reinstate Monica Jul 31 '17 at 13:49
• @Yakk, added a follow-up. – o.m. Jul 31 '17 at 18:15
• I LOVE this answer! What an imaginative way to get around the problem. Illegal immigration! Of course, some liberal do-gooder would eventually notice that a substantial fraction of immigrants were not making it into the work force, but +1 for an absolutely creative proposal! – JBH Nov 4 '17 at 1:19

One single method would not be sufficient. After all, 2,000 people a day is quite a number of people to hide. Since there are 196 countries in this world, 2000 people per day averages to about 10.2 people per country per day (2000/196 = 10.2.) The number of people from each nation would be proportional to their population. For example, assuming 7.3 billion people, China would contribute 375 people, India 345, USA 89, and Indonesia 70. North Korea, at 25 million, would contribute 7 people.

Servant class

The first few decades of their exile, the aliens would be consuming the feedstocks that their people left them, as they developed their food sources while they researched humanity. Rather quickly, they realized that they needed a corp of trusted intermediaries to carry out their plans. So they covertly kidnap a few hundred young children. They are raised to worship and serve the aliens. After these children grow up, they can interact with 'wild' humans. While Captive-bred humans would not typically be used as food.

Third-World Prisons

There is plenty of people in prisons worldwide. In developing nations, political and economic forces conspire to cause high mortality rates and lax oversight. Servant class members could negotiate off-the-book 'transfers' for a few dozen from each prison every month without notice.

Industrial Accidents

Working in developing nations can be dangerous. In China, for example, 66,000 people died in 2016 in workplace accidents. If a worker now-and-then were to 'die' and require a closed coffin, who would notice?

Ethnic Cleansing/war zones

If a regional conflict involves ethnic cleansing, genocide, and barbarism, any missing towns or villages would be attirubted to the general violence rather than carniverouis aliens.

There are classes of people in every country whose disappearance would not be notice (or actually welcomed.)

There are also criminal enterprises (read gangs) who would willingly harvest said people for a price.

Feedlots

Since a lot of their stock will be coming from areas with poor nutrition or unhealthy conditions, I would assume that the people would be transported to a feedlot, where they are cleaned up (gotten off drugs, treated for diseases, etc) and fattened up before slaughter.

• should be noted that some so called countries have fewer than one thousand inhabitants, so taking 10 people out of them is noticeable;) – Ando Jurai Aug 1 '17 at 14:26
• I posted a clarification. – Andrew Neely Aug 1 '17 at 17:31

You don't say much about the aliens, but 60t of meat each day sure is a big figure. Either they are individually very massive or there is crowd of them. Most likely both. That and the insane amount of people that have to be abducted, managed, shipped, received and prepared on a daily basis makes the question of them staying hidden a matter of months, if not weeks.

Moreover, the wording of your question makes it clear that you designed that question so that it has to be humans that these aliens are fed, thus I assume it's your intent that these aliens eat humans and you chose the circumstances to suit that intent.

What strikes me, instead, is that your conditions actually don't force these aliens to eat humans. With very little - if any - help from humans, they could build food factories. You state that they were given no technology to synthesize meat, but synthetising meat is quite easy, that's called animal life. By breeding insects or even microbes, in modular factories - something that actually is done by humans - they could produce vast quantities of animal food with a way higher rate of protein, less fat and overall better for health than wild human flesh.

Moreover, their activities would be tremendously easier to hide. So much easier that in fact it could be possible to achieve the numbers you ask for without being noticed while having them to consume food that is way healthier than healthy adult human meat, which is what you asked for.

Another inconsistency in your question :

because of certain ethical and cultural considerations, they wish to live in harmony with their habitat and thus they greatly prefer to kill/farm/consume species which they deem as "invasive/"unchecked", species which are causing untold havoc to the ecosystem. This (unfortunately for us) happens to be, according to them, humans.

You could have directly stated that they somehow won't eat anything but humans. But your reason for that, once again, is flawed. Why would they believe that ? They are strictly carnivorous. Such a species would be unlikely to develop such ethics, and if they did, given their technological advance, they would have come up with means to practice it. That these particular aliens, exiled on another planet with all these batteries and stuff and all that knowledge, would be unable to reproduce these processes while being willing to apply those ethics seems dubious.

Another point is that while they are unwilling to be uncovered, they

have no qualms with majorly distorting the status quo

That looks like uncovering their existence.

I believe you should review the base of your story, what you want to have in it and more importantly why, so that you can properly craft it. Make no mistake, I like the ideas you bring up, or else I wouldn't have answered. But it seems to me that you brought up the elements in the wrong order, giving them only one leg to stand on.

Take also into account the realism. Hard science isn't the goal, but some realism is needed. If you insist on having aliens relying on the abduction of more than 2,000 healthy and adult humans a day to subsist, you should be prepared that your story will be about how humans resist to these aliens, because it seems dubious that thousands of actively working people could be daily shipped to Nevada and disappear without raising some eyebrows.

Good luck with your world building !

Alien creates a bio-nano-mech virus/parasite that spreads across the human race. This virus causes a unique, controllable form of cancer that causes a harvestable meaty organ to grow inside the infected human. Once the cancerous organ is fully grown the robotic portion of the virus aids in creating a micro wormhole inside the person harvest (most likely while the person is sleeping ... possibly induced into catatonic state). If discovered it would simply look like the person was affected by some random form of cancer ... the human would remain otherwise healthy.

grape = 5.1 grams
5 gram per week per person
5 x 7 x 200 x 60,000
req 420 mil infected
~1 bil people affected by a cold virus per year
7.4 bil people on earth


This will be a brutal process and is likely doomed to failure.

The average human weighs 57.6 kg.So you're talking about eating about 1042 people per day, on average.

This means no one single tactic is going to feed your group. You must attack the problem (pun intended) from several angles.

## 1. Split the party.

If your aliens stay grouped together in any one area/city, the rapid drop in population will be noticed. So your aliens must split up. There's no way they can stay together. The more they can spread out the better, so no one group of people is the focus of their hunger.

## 2. Look for the unseen.

The easiest targets for consumption, unfortunately, are going to be the people no one notices, no one cares about, or that no one wants. These are the ones that, even if they go "missing," won't get reported. And the reports will go unsolved. This means hitting cities with large homeless populations. Or large populations who live "off the grid," or below the radar. In the USA, this means minorities in inner cities, homeless, etc. In other areas the demographics will be different. But the aliens have to figure out who the unwanted are. (I am not saying no one wants these people. I am saying that, systemically, these people are the easiest to remove from society. And that society as a whole is least likely to react quickly and with determination when these groups have problems.)

## 3. Be flexible.

Hay (sorry, last pun), sometimes humans aren't the issue. Our livestock also cause methane emissions. The global impact is disputed, but there is an impact. So maybe they sometimes switch up and eat some cattle.

## 4. Be mobile.

If they stay in the same spot for too long, eventually someone will take notice and begin investigations. They need to stay mobile, moving from human herd, er, city, to city. They need to coordinate their movements so they all don't end up in the same city. But this way their feed stock can repopulate.

## 5. Sow chaos; reap the benefits.

War zones. Natural disasters. Political destabilization. Anywhere these things are happening, there's less response to claims of missing persons. Tsunami washes ashore and a thousand people vanish. Everyone chalks it up to the water, never realizing the aliens had a quick dine-and-dash. Several countries in Africa are in civil war. No one will notice if a few villages vanish in the midst of this human-induced chaos. Your aliens have to be aware of the global news cycles, so they can chase these sometimes-short-lived feeding frenzy opportunities.

## 6. Self-policing.

They have to maintain law and order within their own. If one of the aliens goes off the reservation (see meanings 2 and 3), the other aliens must re-establish control immediately. I mean, history shows that humans are endlessly obsessed with large groups of people being murdered or disappearing in short time spans. See Jonestown, Roanoke Colony, and other stories. Sure, once or maybe twice this can be handled. But it cannot become a daily habit.

## 7. Slavery.

They may need to keep humans as cattle. Perhaps set up a large reservation where people can be kept, and where their absence won't be noticed or will be difficult to investigate. With careful planning and management, entire towns could become isolated breeding grounds where people never leave. But this is risky. Especially in modern times where global communications are so easy for us humans.

## 8. Future planning

The aliens need to either plan for permanent life here, so begin building procedures to hide within our midst forever, or they need to find a way off this rock, before they are discovered. Without planning, they will be discovered, eventually. Maybe even a dual-pronged planning attack, with a committee focused on long-term earth survival and another focused on escape.

• Note that I'd use similar tactics if I were planning a Vampire society. – CaM Jul 31 '17 at 20:10
• They can create bioweapons and artificial viruses.
• These aliens have no qualms with majorly distorting the status quo.

Okay, then it can be done quite easily. Develop and diffuse - using androids and flying bots - a plague that targets human intelligence. One month later, human civilization collapses and most cities become death traps, incidentally supplying all the meat the aliens might need for an extensive period.

At that point they can harvest a sufficient quantity of humans to set up human husbandry (through droids). You need around 750,000 new individuals per year; assuming you harvest them at age 20, that should work at around 20 million healthy (but quite dim-witted) humans. You could do that with less.

Task zero is to cripple any accidental nuclear option which might be triggered by the plague.

The first task is to harvest and store enough food to tide the human cattle over the first months. This includes livestock, grain storage, supermarkets, army depots and so on. Having the capability of penetrating networks would provide enough intelligence to know where (and when) to strike.

Your second task, in parallel to the first, is to harvest 20 million humans from everywhere suitable and gather them in the pens. If the biotechnology required to inactivate prions exists, for a while they can be self-sustaining - you harvest more than needed for reproduction, cull the weak and slaughter them to feed the rest. If this is not possible, they will need to be fed out of harvested resources.

However, throughout the operations, enough humans will remain uninfected to be able to self-sustain until they're harvested and infected in due course. You might decide to not infect large undeveloped, low-tech areas as a plan B.

At the end of year 1, you have your 20 million human cattle stowed away in pens, and start moving toward a sustainable diet:

It is realistic to suppose that the absolute minimum of arable land to support one person is a mere 0.07 of a hectare–and this assumes a largely vegetarian diet, no land degradation or water shortages, virtually no post-harvest waste, and farmers who know precisely when and how to plant, fertilize, irrigate, etc. [FAO, 1993]

So you also need, say, two million hectares of reasonably fertile land overall. Androids and bots tend to the humans.

You immunize your domesticated humans, then release a second, much deadlier plague over the whole Earth, which is then left to lie fallow.

• Better to avoid cannibalism. Feeding cows to cows results in mad cow disease. Guess what happens when you feed humans to humans... It's not pretty. – Perkins Jul 31 '17 at 19:03
• I don't think aliens would be susceptible to kourou disease, and anyway you just need to discard brain tissues. – LSerni Jul 31 '17 at 19:26
• The aliens might not be, but if you're using cannibalism to sustain your human livestock while you get your infrastructure set up you might end up seeing them all just keel over for no apparent reason, which would be inconvenient. Discarding brain tissues helps, but any nerves at all, including the peripheral nervous system (which is practically everywhere) carries some risk. – Perkins Jul 31 '17 at 19:34
• That's true, very good point. If the aliens don't have a practical way of making meat safe, they'll need to also schedule foraging runs against livestock and any food reserve that might be found worldwide. Their capability of hacking into existing networks should help in the preparatory phase. – LSerni Jul 31 '17 at 20:38

Depending on the capacity of their technology, use their wormholes to firstly abduct victims and replace the victims with androids. If they have sufficiently advanced robotics the robots can run the wormhole capture systems and manage the manufacture of the androids and ensure the androids are effective duplicates of the harvested humans.

Someone should notify the galactic equivalent of the United Nations Organization about the technologically advanced species dumping their dissidents on a planet where the local intelligent species is being preyed upon the illegal imprisonment. To be legal, this process needs the appropriate sanction and acceptance by the authorities of the native population, in this case, humans. Strangely enough, humans might not be enraptured at the prospect of becoming an alien's lunch.

I think that with unlimited resources and logistics, with a good tech advantage, it is not impossible. But even if not revealing themselves, they will drastically change the current state of the world, as a cover up.

I do believe that with enough technology and politics, you could basically get a WWIII. Then, drafts would be organized and represent your whole food income. But you would need to prevent use of mass destruction weapons, which would basically spoil the "food". So this would be by itself a really high skill diplomacy maneuver. Some world wide guerilla style fights would keep the "creation of available food" at an acceptable level.

Now you need to harvest the corps. Maybe being some part of the red cross or anything that would be able to cover up for constant intervention on field. But in many countries, we culturally attach to bringing back the corpse to the family, so some explanations would be necessary on this part too. Probably that guerilla style fights also intercept military flights transporting corpses, so after a few events like this governments would stop using resources to get corpses back.

Even an easier solution would be to create any world scale catastrophe that will cover up abductions. If a zombie apocalypse start, you can easily pick survivors without nobody noticing, you will just need to manage a bit so enough healthy people remain to reproduce.

You need some more, just send a tsunami on a random beach and harvest what you want from the water. Sudden destruction of a big building by a terrorist act can cover up the abduction of the people inside, if you splatter enough blood and members to make it look like they where crushed by the remains.

sometimes, make a plane disappear. Spread a local virus and make the government burn the area. Create a sect and push people to reproduce and to give themselves up to god at age 40, in some third world country. Give free energy to the corrupt military head of the state for full support. There is many other thing that can come to mind.

The main points are : - Make people care about some other catastrophic stuff: war, apocalypse, etc.. - Think of the way you will collect, transport and keep fresh your "meat" - Keep enough lifestock to get sustaining population, even with the huge toll you will take.

• At 5 surviving children/couple and reproduction mostly done at 30, that is a yield of 3 surplus bodies per 2 population per 30 years, or 5% of the population. To yield 3/4 of a million you need a farmed population of 15 million breeding pairs, with 60% of all children reaching adulthood harvested. You'd have to explain the culture and how the harvesting is happening honestly. – Yakk Jul 31 '17 at 13:00
• maybe then add some aphrodisiac in the air, and growth hormones, and supply food to them. Anyway, if ethics are in play, it won't fit : Furthermore because of certain ethical and cultural considerations, they wish to live in harmony with their habitat and thus they greatly prefer to kill/farm/consume species which they deem as "invasive/"unchecked" – ncalep Jul 31 '17 at 14:31
• I'm talking about the human culture, not the alien one. – Yakk Jul 31 '17 at 14:46

I don't want to be a buzzkill, but I feel there are two major flaws in your premise.

1. You say your aliens are essentially carnivorous, which means they basically only eat meat and very little plant matter, yet they have a high regard for nature and wish to live in harmony with their habitat. If the (presumably, though you don't specify) small number of aliens on Earth need to eat 2000 humans a day, what exactly do their brethren back on the homeworld eat? How does a carnivorous species evolve to a point where they are unwilling to procure the sustenance necessary to survive?
Veganism and vegetarianism can be explained in humans because we can survive quite happily on plant matter, but the way you phrase your question suggests this is not the case for these aliens. Without farming or hunting animals they could not exist. The idea of living in harmony with nature (which involves not farming or hunting) and being entirely carnivorous are mutually exclusive as far as I can see.
2. You say the aliens view us as an invasive species that has grown unchecked and that is why they are willing to harvest us, and also that they are happy to disrupt the status quo and topple governments etc. but that they do not want to reveal themselves. This doesn't really make sense. If humanity is seen as a pest then why don't they just use their superior technology to annihilate us (or conquer and farm us). They apparently have the capability to wipe is out or damage us enough to then enslave us, so staying hidden (and trying to remain so) seems a bizarre choice. In fact giving any kind of consideration to what we think or feel would be like humans trying to make mosquitoes unaware of our existence and undisturbed by our attempts to eradicate them...

So I would say the answer to your question is that the aliens wipe out humanity using their superior technology (and feast on the dead while doing so) and then allow the planet to return to some kind of balance / harmony where they then practice whatever method of procuring food they would have used on their homeworld (which I would presume would be some kind of sustainable farming or hunting as it's the closest fit to what you've described)

1) Put up a legitimate front or two. Something which gets money - a bank? - something showy which awes people and makes them respect you - rocket ships, sports cars.

2) Use your technology to promote automated self driving cars, use your influence to promote tunnel systems. A "Hyperloop", automated people, tunnels.

3) Start a really innocent boring company. It's going to be really hard to march the streets of big cities and take homeless people and ship thousands per day to your secret location. But what if the population of the cities actively wanted to get into a self-driving pod where they weren't paying attention, if it was normal to vanish underground into a warren of disorienting tunnels with no GPS service? To the point where the desire lead to connecting every city with every city?

Homeless people would naturally head for the shelter of the tunnels as well, and they would be harder to notice there than in subways where people are walking.

When your self-driving taxi turns up, are you really sure it's the right one?

4) Encourage a service where people get into one of your self-driving cars for a surprise destination adventure.

When you have tunnels connecting all the major metropolitan areas of the planet, and tunnels connecting into it going back to your lair, and millions of journeys per day, siphoning off a few people, automated collection of people, will be a small matter.

5) Build up a great set piece with an exotic name, e.g. 'Mars', somewhere people can "go" to "live" with your "help", but nobody can go and check on them, because it's remote and expensive and has unreliable communications links.

6) If you use your Alien engineering skills to make the tunnels deep enough, some of the food could be delivered cooked, but you'd have to pay special attention to making the vehicles head resistant enough.

1. Partner with an existing totalitarian state, where, by definition, the government does things without having to explain why.
2. Forbid technology transfer and wealth transfer to outside.
3. Use technology to elevate standard of living of every citizen way beyond the global average, and to reduce working hours to three or four a week.
4. Forbid more than one child per woman.
5. Allow free immigration for anyone in the world, and pay for their safe, comfortable transport, with one caveat: a lottery will select 2000 incoming immigrants per day, to die and disappear. Promise anesthesia and a humane ending, you may as well deliver on the promise. Their ultimate fate is obscure, but everything else is transparent. Allow families and other groups to face the lottery as a group, such that each individual's chance to go remains the same, but either they all go, or none of them goes.
6. If absolutely necessary, ship the meat to the U.S.A. disguised as animal meat. But consider relocating to the partner country.
7. Monitor the outside world population. If it starts shrinking too much, you may have to limit immigration to a large amount.
• This is actually really interesting. Yet somehow, I feel like, even if the chances of being killed would be tiny, people would still not want to face those odds. – AngelPray Aug 1 '17 at 22:29
• @AngelPray: in our real present world, many migrants routinely face relatively high risk of death - and many do die. And that's without full citizenship and guaranteed wealth the moment they enter. – Emilio M Bumachar Aug 2 '17 at 11:39

### Fake plague

1. Create a real plague. It's quite communicable, so dead bodies have to be cremated. Second, create a method that will successfully combat the plague in around half of all cases. The method should require isolation in such a way that it's easiest to group the sick in one area. For example, perhaps exposure to sunlight and fresh air in a low humidity environment works. So they have to get the sick to an isolated and dry location. Perhaps in the Nevada desert?

The cure does not have to work as described; they just have to make it look like it works by healing 50% of the people who try it.

2. Create a fake plague with the same early symptoms. Then people will be sent to the place for the cure. Let it wear off. Announce that 50% died and were cremated. Eat them instead.

Possibly the real plague and the fake plague are the same thing. Just there's a hundred percent cure that they only apply at all in the one location. Because there's a hundred percent cure, they never eat sick people. They cure them first, after updating them as dead in the computer system.

Because they are at a hospital, the aliens can give their androids bulky suits and move around at night. Insomniac patient? Sedative injection and a place on the dinner menu.

The plague can be spread by fake (android) mosquitoes or similar. So outbreaks can be scheduled and targeted.

Everyone will know that something is happening, but there is an easy explanation there. They will never look the extra step beyond the obvious explanation. Except perhaps for the occasional Fox Mulder type.

EDIT: A solution to the problem is to create a socially-acceptable method of collecting bodies such as cyronics. People disappear with no near-term expectation of reappearing. An example of advertising/PR that the aliens could take advantage of is below. It uses an existing company (Google's Calico) as the basis of the example.

Calico, Google's life extension company, finally takes off. And is free for everyone.

Wish you could live longer? What about your loved ones? In Calico, we are building the biggest Cryonics facility in the world. The best part? Is free for everyone.

As a Google-founded company, we share the same mission: to make the world a better place to live. That's why we don't charge users for using our services.

How does it work? It's pretty simple. Once you sign up for using our services, you will receive a tag and a chip that states your ID number. Doctors arriving the scene have clear instructions to not to try to resurrect you, but to call Calico. Once a Calico doctor arrives, she will begin the process of preparing your body to be frozen, instead of harming it using conventional resurrection techniques.

You will be placed on stasis, and translated to our huge underground facility under the vast Nevada desert. Fear not, our facility is completely isolated with the most rigorous security that you can expect from Google.

Years in the future, when science and medicine advances to help cure your cause of clinical death, you will be de-frozen and given a second chance to live.

How is this free? You may be exposed to advertisement from our trusted partners during your state of stasis. This is completely optional, you can opt-out before signing up.

Nevada News. Millions of people are signing up to the new Calico service from Google. In an unprecedented way, the promise of longer lifespan combined with Google expertise, are making the cryonics generation a reality. The extravagant newly appointed CEO of Calico, say this: "We are very happy to be helping the humanity on reaching a new level of happiness. And they help us in turn". We are still not sure what does the last sentence mean, but the world furor on freezing their bodies before death doesn't seem to care much about that.

• Why is this being downvoted...? This is actually an excellent answer. – AngelPray Aug 2 '17 at 6:25
• Most likely because, dealing with an actual company, the expression of the answer is indistinguishable from advertising spam. – JBH Aug 2 '17 at 13:24
• @JBH But it's obviously not advertisement... ...What sort of advertisement would that be? "Come freeze yourself at Calico, which may or may not be the larder of some very hungry human-devouring aliens!" Did people just read the first line and assume it was an ad? – AngelPray Aug 2 '17 at 16:12
• @AngelPray, "obvious" is in the mind of the beholder, and whenever I hear someone claim, "i's obvious..." what I suspect I'm really hearing is, "I'm too lazy to make what I tried to do more clear to the body public...". I added the necessary paragraph to give context to the "answer." With that context, I'm willing to remove my downvote. But it'll return if it or something like it doesn't remain with the "answer." – JBH Aug 2 '17 at 17:00
• @JBH Well in this case, what you're hearing by the claim "it's obvious" is "I had no part in writing the answer (and thus it is strange to have someone call me lazy because of it) and yet to me it does not come off as advertisement in the slightest. Moreover I am perplexed as to how anyone could ever think it was an advertisement". – AngelPray Aug 2 '17 at 18:04

According to Moore, Carole. The Last Place You’d Look: True Stories of Missing Persons and the People Who Search for Them. New York, NY: Rowman & Littlefield Publishers, Inc., 2011.

Approximately 2,300 Americans are reported missing—every day. This includes both children and adults. This does not include Americans who have vanished in other countries, individuals who disappear and are never reported, or the homeless and their children

A number higher than your 2000. You could add people from Mexico, include those homeless ones (government can scan and check them at shelters and send healthy ones "for additional tests").

The question is do they need to have slaughter house on site or can get frozen or preserved meat? If first then their Nevada location would be good as no one would notice intoxicated, lost or buses full of people going around and out of Las Vegas. If the second then it's even better because no one would notice Pizza Hut and McDonalds trucks.

• but how many of those 2300 turn up again? – Separatrix Jul 31 '17 at 8:18
• According to the source there is 900000 people missing per year. I assume that is adults and children as International Centre for Missing and Exploited Children states that 800000 children are missing per year. I assume the 2,3k are from that "year number" divided into days. And as that number rise smaller number turn up than is missing. – SZCZERZO KŁY Jul 31 '17 at 8:39
• From the UK figures: 250,000 reported missing a year, 16,000 missing for more than a year. The vast majority are quickly found or return by themselves. – Separatrix Jul 31 '17 at 9:27
• A lot of the "missing" will also be repeat offenders, children who run away every couple of weeks before being found. The number of people involved is much smaller than the number of reports of missing persons which is what we're talking about here. – Separatrix Jul 31 '17 at 9:29
• There are also people who are not reported missing. I think until we will sell those people to the aliens there is no way of knowing how many there are. – SZCZERZO KŁY Jul 31 '17 at 9:44

Influence the government to mandate all dead bodies be "donated to science"

Approximately 1 person in 50,000 die each day. To have 2,000 bodies per day, you would need a country with a population of at least 100 million to satisfy the requirement. Assuming daily variations, some dying of sickness, and some people refusing to "donate", lets assume we need three times this amount to meet the requirement.

The US has a population of over 300 million.

Have the aliens influence the US government to mandate that all citizens donate all dead bodies to science. Create some fake reason(s), such as:

• Metals buildup in the body combined with a scarcity of a specific metal
• Cancer rates are soaring and research must be done - soaring rates are caused by the aliens
• Public told that cryogenic research has perfected human storage

It's been done, essentially, in John Norman's Gor novels.

Though the numbers required there weren't mentioned, the aliens involved were eating not just humans but any meat, and avid and feared hunters as well as warriors.

They employed humans to act as slavers for them, capturing and buying (on legitimate slave markets) humans for transportation to their location (in this case an artificial moon in orbit around the planet). There these humans would be used as cattle, and bred, as well as employed as traditional slave labour and as pets. The humans thus farmed were trained to obedience and fattened for slaughter, then driven to mostly automated slaughter houses.

While the level of technology is higher than what your aliens are likely to have available, the concept might well remain. Though Nevada is a bad location because of the absence of a large scale slave trade in the modern USA (you need to go to Africa or the Arabian peninsula for that) human trafficking in illegal aliens can probably substitute. Mexicans promised a better life in the USA by human traffickers are instead delivered to your alien enclave, there to be either ate on the spot or used as livestock in their breeding operation.

They could even organise hunting parties in the scrublands along the Mexican border, though on earth, more civilised then JNs Gor, the evidence that'd leave behind is likely to cause trouble quickly.

Do what my people are already doing.

Step one: Kidnap one healthy human.

Step two: Take his muscle cells. Breed them in alien equivalent of petry dishes. Exercise them with electric shocks.

Step three: You now have as much meat as you want. Keep human alive for extra resources so you do not get Cloning Blues from making a copy of a copy. Always copy an original again after harvest /200 cell generations.

Step four: Kidnap another human once this one dies.

There are very good reasons why humans pick beef/chicken/turkey as a primary meat source, rather than crocodile/lion/piranha.

1. Nutrition: Herbivores have more fat as a rule than carnivores, meaning more calories per kill

2. Risk: Falling into a pen of chicken vs falling into a pool of piranha's

3. Cost: To feed the carnivores, one would have to first breed the meat they need to eat; making the process just that more expensive.

This would mean that to bread humans for meat, one would ultimately bin the idea of feeding them animal products, (other than waste) in the same way we feed chickens which would actually happily eat anything on the floor they can scavange.

If one is attempting to do this secretly, the first step would be to try and make everyone a vegetarian, or pick a location where they are already. The other requirement would be a location where life is cheap. The cheaper the life, and the more common death to various illnesses or abuse, then the more likely you'll be able to get away with it. Also these populations are more likely to have a high birth rate; essential to your high output.

Putting these requirements together, I'd consider India as a likely candidate; performing 200 abductions / day in the poor regions is probably going to be largely unnoticed, and at the very least unrecorded.

Sounds like the aliens have more than sufficient technology to farm humans at the bottom of the ocean. Just need to dedicate enough power to farm some form of vegetables to feed the humans and then you'd just need maybe 2,000,000 humans on a farm and then you can kill 0.1% per day and it would be fully sustainable.

60,000 kilograms is about 1,000 people. In 2015 there were 11.3 million illegal immigrants entering into the US. In 2014, 414,000 illegal immigrants were deported. That is more than 1,000 per day.

With the technology you describe, these aliens should have no problem tracking groups of immigrants and intercepting them in isolated areas with a wormhole that dumps them in their holding pens. They would only have to catch 1 out of every 30 illegal immigrants to come up 1000 per day. They can also convince the government to contract them (using their humanoid robots) to be the company that deports illegal immigrants. Using some of those to cover any shortfalls in their captures.

This makes for a horrific story, yet with hooks all over today's discourse (or lack thereof) on immigration.

• 60,000 kilograms of human meat is actually about 2,000 peoples worth when you remember that only 30-40% of a human's body mass is muscle. – AngelPray Jul 31 '17 at 22:00
• @AngelPray - while OP did say "meat", many carnivores consume their entire pray, fat, bones, and all. Think crocodile, shark, etc. But if you go with only muscle, 30-40%, average to 35%, the figure would be closer to 3000. – user11864 Aug 4 '17 at 15:45

Nevada is probably a bad choice due to population density. It has Las Vegas where you could get prostitutes, homeless, and etc reasonable easy. If you could teleport, or otherwise get an agreement with the government you might be able to get prisoners. Otherwise Nevada is sparsely populated.

Note: To augment the numbers of people do the following: If you have wormhole tech steal people from North Korea, nobody will care what they think. Just make sure it can't be tracked back to the US. Also illegal immigrants aren't a bad idea especially if they have criminal records.

Maybe if the aliens can take over sanitation they can get food from garbage trucks, landfills, and maybe even human waste from our sewers. Think how much meat slaughter houses and butcher shops discard each day. Assuming they have advanced food sanitisers they can clean the food we as humans discard every day for consumption either by them or their breeding stock. They probably just extract the nutrients and inject it into their breeding stock.

The aliens will have to have food to sustain them on their long journey. They are going to need to bring enough extra to setup a breeding farm of humans.

Long term, you need to hide a population of humans for the sole reason of breading. You don't want to educate anyone or they will know they are slaves or captives and try to escape. They only need to have each woman pregnant with as many babies as her body can handle, over and over again.

30 *9 months =240 days *2000 = 540,000 babies in 9 months. I don't know how your going to sustain that. Say it takes 13 years for the woman to be able to get pregnant. That is 4745 day * 2000 or 9.5 million people dead before they get the first round adult babies.

The aliens will have to have advanced pregnancy tech including artificial wombs.

Now if the aliens can go around to people and get genetic samples from a wide variety of people, and turn those into babies back at HQ then it would be significantly easier. Say with a hand held scanner they steal eggs and sperm from random people as they walk by without them noticing. Go to stadiums with 10,20,or etc thousand people harvest 100 or 1000 sperm/eggs each and you have a lot of future people. Only enough humans would have to go missing to feed themselves during the growth cycle.

You will need to have a tremendous under ground cave to hold enough for regular harvesting, plus a good safety margin. I get Nevada is the place to hide that.

With such advanced knowledge in biology and physics, the aliens should figure out how to clone humans.

This will drastically reduce the number required abductions to a reasonable one. If for the sake of the story you can't abduct only one human and clone him infinitely, you may introduce the idea that the cloning process slowly sickens the human and makes him poisonous after being cloned X times.

I like this topic as there is so much to say. Nevada is not a bad place as it would help drowning observations of UFOs into the urban legends and actual military flights observations. With their tech, they could even stay undetectable to military.
As for targeted populations, I would not take developed countries for starters, or at least not their advanced areas. And that leaves a large part of the world (rural china, russia and europe, northern countries during the prolonged night periods, south africa and desertic north africa).
I would also take on touristic areas (thaïland, small islands) or keep them as backup in case things get awry.
You can also attack cruise ships (6000 persons on some ships, 3 days worth of stocks). I would vary with plane abductions, and town obliteration in aforementionned areas, preferably in war zones. I could even use large scale massacre from human to take a pause from killing myself.
Drones and all would be of great help. I would use androids to substitute to key people (investigators, heads of departments, high level techs) to be able to inform from them and act according to my plans (keeping them as trump cards for twarting any counteroffensive or discovery of my lair).
I would use the human satellites to get infos and would spoof their signals to say everything is ok. this would delay discovery.
One interrogation is the scale they can use droids and drones, and if their wormhole tech is transportable enough for these to be deployed without some kind of base ship to transport them in the hole first...
But using the wormhole tech could help mislead people, for example showing abducting spacecraft to originate and to shuttle to some country, then disappearing, helping for example to start a war between neighbouring countries, helping dissimulate the abduction into the chaos. Then could even go for obliteration of large cities by using their tech to phase communication (or whole cities) out, then abduct all people (tempus fugit style, or in real time hunt for your prey style), then destroy the cities with tech that would make think outside world about a large scale attack (-nuclear- bombing?)

• I just feel like if we were the dungeon masters here, but with the dungeon getting out in the world, or as a XCOM reversed campaign;) – Ando Jurai Aug 1 '17 at 14:18

Wormhole tech is the important factor here, that gives you instant access to anywhere in the world. That means you can hunt, kill, and remove people from anywhere in the world at any time and take home the meat. Assuming that you have good disposal systems for the leftovers, which you do because you can use a wormhole to dump it at the bottom of the ocean trench of your choice, you can kill any number of people without any inconvenient evidence coming to light. There are a number of authors (Jim Butcher for one) who have pointed out for one reason or another that large numbers of people disappear on a daily basis across the globe and of many, if not most, of them no trace is ever found. With Robotic servants the XTs need never leave home but with good wormhole tech they could go out hunting themselves as long as they made sure to get their target, and eat anyone else who might spot them. Your XTs wouldn't even need government co-operation to keep themselves feed.

• Wormholes to drop "waste" to the bottom would be a waste (Hyuck Hyuck)... why wouldn't you use the waste as fertilizer? Grade-A Compost? Sell it to farmers to make food to fatten up the next round of Grass-Fed Humans (Preferable anti-vaxxers - since they are GMO free). Aliens need to be healthy and support a healthy food cycle after all. – WernerCD Jul 31 '17 at 15:16
• @WernerCD Nice! I hadn't considered that option, any non-obvious disposal system works. The anti-vaxxer bit is a good touch too, you'd probably want vegetarians or vegans for the best taste, although that may go against their environmentalism as both groups make a far lighter dent on the global ecology. – Ash Jul 31 '17 at 15:42

Since they have access to wormholes, they could kidnap enough humans (slowly growing the number until they have what they need for harvesting 2K per day) and wormhole them to some other planet, creating a human farm outside any possibility of humanity learning about it. Another answer said it would require around 15million humans in order for the population to reproduce at a sustainable rate. Not very much, if divided by some larger groups/camps.

On a plus side, since they are predators they maybe would sometimes like to hunt those humans instead of just processing them -- so they would have some sort of nature preserve.

They could create robotic oversight, so that the kidnapped humans don't get ideas about organizing resistance, but basically, once the initial generation would be eaten, the next one would be without any knowledge.

So, let's say 100 settlements with 150'000 humans divided evenly across some planet, in places where they can thrive and be reasonable self-sufficient; robotic killers/guards to make sure everything stays in these limits, and the processing plants.

If anything goes wrong with the population there (epidemic, earthquake, meteor strike), they would just resupply some more from Earth.

All that said, I find the initial premise of them choosing "species which are causing untold havoc to the ecosystem" laughable. This such a human-centric view. Any sane alien couldn't care less about our current ecosystem, as the only creatures to whom it matters, are us. All that Gaia crap presumes nature having a balance, which we can upset. Guess what. There is no balance, there is just something which WE like, and which we can destroy and which will regrow into something different that WE maybe don't like/can't survive, but which will be GRAND for the new species that used the hole we provided.

• That's a stupid way to think of it. If they are really advanced, even carnivorous, they can respect nature and be "livestock farmers". I am not into esoteric gaia thing, but as far as systems go, ecology and balances are not illusion. And they can consider earth to be their new home, so don't want to destroy it. – Ando Jurai Aug 1 '17 at 13:59
• @AndoJurai There is nothing stupid about it. "respect nature" is a stupid thing until you acknowledge that the nature you respect is the particular nature that is so comfortable to humans and is completely different from nature that existed, for example, during ice age or any other major era. I bet if there were sapient mammoths at the end of ice age they would deplore the melting of European ice sheet and thinking heavily how to stop global warming. Likewise the predators of OP may as well be from a desert environment and despise the humid jungles and plenty of water Earth basks in. – Gnudiff Aug 1 '17 at 14:20
• As I read it, they respect nature equilibrium, so I guess in their views, they would go together natural climate changes, not be like "we have to stop/accelerate global warming". While they would attack humans for being responsible for disturbances in such equilibrium. Also, I chose this word because your justification to your argument felt like a jab to people fighting climate change/global warming, like it was only by comfort and because we can't accept natural changes, while this is not natural. Sorry if I was mistaken. – Ando Jurai Aug 1 '17 at 14:47
• @AndoJurai I feel there is very much cherry picking when talking about "natural". Climate change by humans is a worrying thing. I used to worry about it very much, but since some time and material read, I am not so sure about both the implications and what needs to be done. At any rate, global warming would be bad for us and the current balance of life, however, it seems obvious to me that other species will arise or benefit from it. So I am not concerned about climate because of nature, because in the broadest sense nature and life will do fine. I am concerned about what it will do to us. – Gnudiff Aug 7 '17 at 7:36