For those unfamiliar with the Lovecraftian-inspired story, the Insects from Shaggai, aka Shans, are insectoid, sentient creatures with 12 limbs that can 'phase' into another organism's brain and begin exerting influence. This can take the form of direct, overt hijacking of the host's nervous system, but can also take the form of pavlovian conditioning where the Shan punishes and rewards its victims by showing them choice memories. In the event of the host trying to rebel, the Shan also has the 'nuclear option', where they can drop a memory so horrific it shatters the host's mind utterly and completely.

Basically, my question is: what would a less Lovecraftian Shan more grounded in actual science look like? An anatomically correct Shan should

  1. Have 12 limbs
  2. Be sapient and intelligent
  3. Be insect-like, without being a crab or centipede.
  4. Be about the size of a typical American pidgeon.
  5. Be able to somehow enter a sentient host's body (not necessarily via phasing through matter) and exert some kind of influence over the host.
  6. EDIT: At least 2 of the above limbs must be devoted to wings that make it capable of flight.
  7. EDIT: The creature must have the majority of its mass beneath the skin level of the host.

7 Answers 7

  1. Have 12 limbs: Easy. They are from another planet.

  2. Be sapient and intelligent Maybe you could get rat-level intelligence in something that size. There are no small sapient animals so either give up on number 2 or give up on science-based.

  3. Be insect-like, without being a crab or centipede: Easy. From another planet.

  4. Be about the size of a typical American pidgeon: You cannot have this and also have flight. Pigeons are about four times heavier than the largest flying insect.

  5. Be able to somehow enter a sentient host's body: The creature lays eggs in a pregnant woman and the young grows to replace the foetus. This way it remains in the body. It has sensory tendrils that extend outside the body. Through which orifice is up to you. . . . and exert some kind of influence over the host: The creature influences behaviour by injecting chemicals into the host. Pleasure chemicals when it does the right thing and pain chemicals when it does the wrong thing.

  6. At least 2 of the above limbs must be devoted to wings that make it capable of flight. See 4.

  7. The creature must have the majority of its mass beneath the skin level of the host. See 5.

  • $\begingroup$ I said about the SIZE. They can easily be MUCH lighter than a typical pidgeon. $\endgroup$
    – Brinstar77
    Commented Apr 29, 2022 at 22:53
  • 2
    $\begingroup$ @Brinstar77 That's even worse! $\endgroup$
    – Daron
    Commented Apr 30, 2022 at 12:57
  • $\begingroup$ I got a few issues with this. 4. Insect-like doesn't mean insect and there were much bigger flying insects in Earth's past. 6. Maybe it undergoes metamorphosis into a flying impregnation stage after the host has died. $\endgroup$ Commented May 11, 2022 at 6:39
  • $\begingroup$ @TheDyingOfLight I believe the larger flying insects are attributed to more oxygen in the air. $\endgroup$
    – Daron
    Commented May 11, 2022 at 12:43
  • $\begingroup$ @TheDyingOfLight What's the significance of "Insect-like doesn't mean insect "? $\endgroup$
    – Daron
    Commented May 11, 2022 at 18:44

Delusional parasitosis.


... Other than their delusion, patients usually appear to be normal. Most patients describe the infestation as being on or just under the skin, in or around body openings, or internal (particularly in the stomach or intestines)... The typical DP patient has suffered from the infestation for some time and has seen numerous physicians and other professionals (eg, parasitologists, entomologists, and exterminators). Many patients describe previously seen medical professionals as uncaring and incompetent. The Minnesota Department of Health (MDH) receives many calls from DP patients with such stories... The patients often submit abundant samples of human tissue, lint, scabs, dust, and other objects for identification as parasites and strongly reject negative findings by those who examine these samples. Self-mutilation can occur in severe cases. The wounds appear in areas accessible to the patient, where they have attempted to excavate the parasites. Many DP patients have tried a long list of remedies, including potentially dangerous levels of pesticides. Patients often have detailed records of their findings, complete with diagrams of the suspected parasite. In some cases, the patient’s medical history is convincing enough that family members secondarily share the delusion.

The infected person has done research and arranged (by a variety of means) imaging tests which have allowed her to reconstruct the basic shape of the parasite she harbors. She has given up trying to extract or poison it and now is trying to come up with some long term management strategy. She has a journal and has empiric data to understand how it can affect her and to some degree how she can affect it. She is unsure of its motives or even if she would be able to understand its motives, but she is pretty sure that there are others. She wants to help the others using the knowledge and strategies she has put together over the years. She is intelligent and convincing.

No laws of physics are broken here.


Have 12 limbs

Be some kind of insect

These requirements are in direct conflict. If it has 12 limbs, by definition it is not an insect. But if you just mean "arthropod", then there's no problem. It's some kind of crustacean or centipede.

Be sapient and intelligent

Be about the size of a typical American pidgeon.

There are plenty of arthropods that can get that big; most of them are extinct, but modern coconut crabs can get as big as a cat, so "pigeon-sized" is entirely possible--especially if it's more centipede-like, giving it a larger surface-to-volume ratio for breathing.

Arthropods are not known for being intelligent, but many birds are; crows aren't much bigger than pigeons, and are quite intelligent, definitely sapient, and capable of tool use. So, your alien arthropod just happens to have lucked out and evolved the more efficient neural architecture of birds, rather than that of insects or mammals.

Be able to somehow enter a sentient host's body (not necessarily via phasing through matter)

Does it have to be completely inside the body? There are plenty of real-world endoparasites, and it could just cut its way in. But it might be more useful to remain mostly outside, where the Shan can still use its own senses to verify what's going on around it, rather than having to try to tap into an interpret the host's nervous system. It would be much simpler to just sink pincers into the host's flesh to latch on and permit the delivery of toxins--or perhaps burying the mouthparts in the host, like a tick, to suck nutrition out and deliver toxins.

and exert some kind of influence over the host.

That's what the "deliver toxins" bit is for! There are already plenty of real-world parasites which alter the behavior of their hosts--including some parasitoid wasps, which are in fact insects. The Shan are just a better version of that--they inject a drug which naturally makes the host feel positively towards the Shan and want to do stuff that it thinks would benefit the Shan. But, because the Shan is itself actually intelligent, it can do slightly better--it can also inject tailored drug mixes which trigger pain, aversion, happiness, or euphoria when it notices the host doing things that it dislikes or likes, and so condition its particular host to do exactly what it wants.

  • 1
    $\begingroup$ It has to be completely inside the body. It also has to be an insect; specifically, an insect with wings. $\endgroup$
    – Brinstar77
    Commented Apr 29, 2022 at 16:56
  • 1
    $\begingroup$ @Brinstar77 If it is specifically an insect with wings, and you count insect wings as limbs, then you have 10 limbs, max. Otherwise, it simply is not an insect--so your requirements cannot be met, by definition. $\endgroup$ Commented Apr 29, 2022 at 21:11

There are many issues here. First, 12 limbs is too many for an insectoid species. Furthermore, the various constraints on the wings are quite contradictory. Finally, their size is a serious limit to their abilities as an endoparasite

We'll look at the first and second issues together. The wings need to fulfill certain criteria, which in this animal could be hard to fulfill all at once. Firstly the wing must be balanced, so that the centre of mass is directly in line with the wings. The wings must also have significant muscles to achieve flight. Because of this, the wings must be high up on the body, necessitating a tetrapodal skeleton if they are to be limb-based. This presents an issue: Tetrapodal wings require external musculature, which takes up a large portion of the available body. This is not an option for this hypercrural being. The only real option would be to place the wings at the extreme rear of the thorax, with the muscles connecting to the base of the thorax bones internally, and exiting to the wings out of the thoracic outlet. This, however, will put the wing webbing across the abdomen, which could seem uninsectoid. It also necessitates a lot of mass in the rear of the body. For the rest of the limbs, the issues are not so great. Simple tetrapodal legs like a lizard, with compacted muscles in the trunk, should serve well enough as the legs

The issue of size as an endoparasite is a large issue. Most animals don't have enough space in their bodies to house a foot-long worm. There is also the issue of getting in. The only option that I can see would be for these species to replace the genitals of their victim. This would involve gnawing a hole through the genitals and crawling inside, before connecting to the host's blood supply and nervous system. From there, it can emit specialized drugs into the host's body to warp their behavior and personality, as parasites tend to do. This arrangement would also require some way to redirect the host's urine, perhaps through the insectoid's body

This should solve most of the major issues with the anatomy of this animal


Likely not happening like you'd like it to.

  • 12 legs: We have arthropods with more than that, not big deal, especially since insects themselves likely come from ancestors with much more than 6 legs.

  • Be sapient, intelligent and pigeon sized: Crows are not too different from pigeons size-wise and this is clearly an alien in many ways. Possible, but don't expect human-level intelligence without some hard handwaving.

  • 2 of the legs are wings: not impossible, but definitely not doable with standard arthropod biology. Been there, asked that, here's a shameless question that might help you if you want membranous wings on your arthropod.

  • has to shove most of its body into the host and be able to influence its behavior. This is the tricky part. The behavior part is surprisingly not crazy and is in fact done by many bacteria and fungi, especially to simpler animals like, well, insects, also being doable through hormones to an extent.

If we push it a bit, the arthropod alien makes use of special cells that can go through the blood brain barrier and slightly change their behavior, with the insect keeping communication with said cells mostly through special hormones in a more complex negative feedback situation. The bigger problem here is the "gotta be inside".

Close your hand into a fist. If you're an adult that's about half the size of your heart. Now picture someone's trying to shove no less than 5 of those into your body, which is already built with essentially no vacant spaces. It becomes worse if you want any of that inside the cranium, that's a recipe for cramping up the brain, which is itself a recipe for achieving a freshly created human corpse. It's not crazy for an animal to burrow into another, especially an arthropod, but the problem here is that the size difference isn't nearly big enough for it not to be a problem.

enter image description here

The best potential course of action would be a "long boy" approach: your "insect" really looks more like a giant centipede (like the one above) with wings, having a flattened body and powerful mandibles. It paralyzes the host with its venom and burrows in, placing itself under the skin parallel to the spine. It then secretes a mixture of secretions that accelerate healing and camouflage itself from the immune system to prevent any unwanted infections, injecting its "mind-control" bacteria-like cells into the bloodstream along with feel good hormones such as serotonin and dopamine. From then on it lives in the person, having minor effects on their behavior, but nothing like what you'd probably expect from an unassumed magical (oops, I mean sci-fi) parasite that's capable of mind control.

This is probably as close as you can get from anything functional that's not outright impossible to exist within our world. Our brains are complex as hell, and out of influencing the host to favor practicing certain actions or favoring being near something (like seen in toxoplasmosis), you're mostly out of luck, and you're definitely not achieving something like actually commanding the host unless you completely throw away the sci part and keep only the fi.


okay! this ranks up in a top percentile for odd questions, but i think the answer is straight forward.

** EDIT the two conditions added

  • devoted to wings that make it capable of flight.
  • majority of its mass beneath the skin level

make it difficult to propose anything workable.

an insect the size of a pigeon is not going to be able to fly. The strength to weight ratio is against it. Insect muscles operating inside an exoskeleton cannot exert the kind of power needed to operate wings large enough to lift 1-2 kilos. Birds wings have all kinds of design features that give them aerodynamic advantages over what are possible for insectile wings. So even using 4 wings physics and bio-mechanics are against it. And a fundamental of insect wings is that they are fragile, rigid, and cannot fold. **

They have evolved to sapience but are possibly not tool using as their modus operandi is to take over creatures that can do all that nasty manual labour for them. This means the 12 limbs need not have manipulators .. except for whatever is needed to get food to the food inlet/orifice (mouth). Lets say 2 for that leaving 10 for walking.

Now the use of the word "Phasing" to describe how the parasite enters the brain dodges a whole lot of problems that would make it hard to explain how a mechanical connection would work. So the beastie has some way of partly dematerialising so that it physically overlaps the volume of the target creatures brain.

** EDIT the question specifically said "phasing" which in modern scifi terms means two objects sharing the same physical volume in some manner.

Any method of mechanical attachment requires that we equip the insect with something that would allow it to enter the body of a target organism without killing it. But this raises a host of problems, not least of which is what to do with the wings. Additional problems include how to keep the subject from bleeding out from a pigeon sized wound, how it would connect to the nervous system, and how it would extract itself when the subject host finally expired. **

So whatever control over matter-space-time they have for the phasing effect could obviously have the side effects of allowing chemical and /or electrical bi-directional transfer of information .. thus permitting mind control at both of the levels required. And clearly the nuclear option is just injecting a lethal level of energy that fries the neurons.

so .. basically it is a 10 legged insect that could have pincers or claws on the end of each leg according to the authors desire.

** A comment from the questioner suggests that he wants an answer that does not break physics, so no "phasing" solutions need apply - in combination with the second new condition any solution is .. doubtful.

A pigeon sized, winged insect might be fit into a human skull, if the brains, and its wings were removed.

For a purely electro-mechanical connection to give the required control over memories the invading insect would have to have direct access to the brain. It cannot co-locate with the brain inside the skull, and below the neck it could only attach to sensory and motor neurons.

So what is left is to make connections through the skull from outside, via its mouth, or other orifice. A connection through its exoskeleton is not possible.

To be able to do this it would need to somehow stupefy or paralyse its intended host, attach itself to the outside of the skull and then burrow in by drilling, or dissolving, though the bone. Lastly it would have to insert fibers or threads capable of carrying neural signals en masse, and then somehow map the hosts memories in the uncharted expanse of the hosts mind.

But an outside connection proposal leaves a large insect clinging to the outside of the skull, which breaks the last condition so .. my answer remains - a ten legged bug that uses phasing to occupy the space between a hosts ears and some kind of "magical" connection to its brain to allow it to read and write the hosts memories.

  • $\begingroup$ Not quite what I want. I'd like this thing to not break too many laws of physics, and phasing specifically does that. $\endgroup$
    – Brinstar77
    Commented Apr 29, 2022 at 15:34

Body size.

The size will be a major trade off point. to the point were I believe the desired pigeon size is very difficult borderline impossible.

  • As a creature gets more massive the costs of flying go up dramatically.
  • As a creature gets larger oxygen becomes an issue. 50 to 200g is as I understand it the transition from where endothermic, oxygen via diffusion rules on the small end and exothermic oxygen via lungs and circulation rules.
  • The smaller a creature is the more challenging it will be to have enough neurons to be intelligent.
  • The smaller the easier it is to hide within the host. Sudden appearance of a 300g lump would set of alarms for most intelligent hosts.

If a Shans has lungs for efficient flight then how will in transition to breathing when inside a body? If a Shans gets oxygen via diffusion it can more easily fly and transition form high oxygen air to low oxygen body.

Comparative masses:

  • Pigeon ~300g.
  • Large beetles such as goliath beetles(50-75g).
  • Coconut crab up to 4Kg. Has lung system, can't fly.

That is most of the requirements push for a smaller creature. The only requirement the pushes for larger is the intelligence.

Influencing a host

Two major means of influencing a host:

Tapping into the nervous system.

Depending on how a Shans taps into the nervous system it can allow for fine grained control of the host. Such as complete hijacking of all voluntary motion.

Direct control of central ganglia would require more extensive growth into host and bypassing even more stringent immune system protections such as the blood-brain barrier.

Control by hormone/chemical means.

This requires the Shans to be an alchemical masters if full range of hormones and signalling is too be used. This would be very difficult to impossible if only due large quantity of signalling compounds. Some of them would require outproducing the hosts own organs ability to clear them. Production organs of these compounds would only be valuable to the Shans when it is internal to the host creature. The chemical library would be different for each host species.

Simpler would be able to apply small selection of carrot and stick compounds. control would be much coarser grained and harder to get desired outcomes. Very easy to get mixed messages


All of these techniques require feedback to the controlling Shans. That is if the Shans makes change, it needs to get feedback that the change caused desired behavior. Which generally means being able to observe with its own sensors. Which is very hard to do if inside the host.

Having the requirement of the controller creature mostly internal to the host yet there is a big requirement of getting feedback to know if stimulus to host is achieving results. If it controller doesn't get feedback, it will not be able achieve much purpose with the host.

Entering host.

Entering a host from arbitrary location is likely to set of pain/touch sensors. This suggests pain killers such as used by mosquitos ticks etc. This would require the controller to be capable of surgery, which is more complexity.

Immune system

Entering a hosts body implies requirement of host immune system suppression/evasion. It usually requires significant co-evolution with a specific host. A large feat. But possible as tape worms and other parasites show.


As an arthropod, twelve limbs, wings, are not an issue.

Reactions to Sharns

If these things existed and were slowly acquiring hosts. hosts there are presumed intelligent. Would there not be a rather extreme response of EXTERMINATE! ANNIHILATE! DESTROY! the Sharns by peoples getting infected?


A Shans requires a complex set of features:

  • Flight.
  • Intelligence.
  • Anesthetics and surgery abilities to enter and hide in the host.
  • Able to make observations while inside the host.
  • Respiration while in flight, respiration while inside the host.
  • Ability to evade suppress the host immune system.
  • Ability to extract nutrients from the host.

Very few benefits Reproductive advantages:

  • Host provides protection.
  • Host provides nutrients.

No benefit to the host has been mentioned.

Tape worms have a few of the needed features and get the benefits, suppression of immune system and ability to extract resources from the host.

Trying to stuff all of these requirements into one creature is likely not possible without specific engineering in my opinion. I have doubts all of that can be stuffed into one creature.

All this to say, Sharns are only plausible for stories sake.


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