Theoretical scenario question I came up with. Unrelated to anything, just a weird idea.

A humanoid species has evolved to appear to humans to be a human female. In fact they have bat-like wings which fold up on their back (which they can use to fly) and a medium-length scaled tail barbed with a strong toxin. It attracts human males, gets them on their own, then kills them using their tails. It needs to eat one fully-grown human male approximately once every two days to survive.

Problem: The race consists solely of females, and they can't be fertilised by human males. Even if they could, pregnancy in a human way would probably put off many males for far too long. And the child either needs to be born old enough to attract males to eat or the mother has to supply extra food, which would be very difficult likely as not.

How can they reproduce?

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    $\begingroup$ My google says a human body has 110,000 calories. Mine probably more. That is 55,000 calories a day for these flying ladies. They had better have some seriously strong wings. $\endgroup$
    – Willk
    Jul 16, 2017 at 20:02
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    $\begingroup$ I am not 100% sure what problem you need a solution to. I think I identified three problems here: 1. how to obtain genetic material so that offsprings aren't a clone of the mother 2. how to have children while avoiding long and debilitating pregnancies and 3. how to feed said children until they are adults. Is that about correct? $\endgroup$
    – Philipp
    Jul 16, 2017 at 20:20
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    $\begingroup$ Also, I don't exactly understand why it is difficult for the mother to supply extra food. Mammals give milk and many non-mammalian species bring food to their children until they are able to gather food themselves. $\endgroup$
    – Philipp
    Jul 16, 2017 at 20:25
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    $\begingroup$ Could it lay eggs instead? does it need to have a complex and flexible brain? Depending on those answers, they could have raptilian brain and can lay eggs, which means they can just lay the eggs that produces semi-grown offsprings and the flying ladies don't have to attend to them as they don't need to teach them anything. $\endgroup$
    – Aus
    Jul 16, 2017 at 20:57
  • $\begingroup$ @Philipp My main problem was that I couldn't think of a way to have them pregnant without putting off men. $\endgroup$ Jul 17, 2017 at 8:49

4 Answers 4


Pregnancy: They could lay eggs, medium size, like football size, which produces a baby the size of human baby. The eggs doesn't have hard shells, but more like an organ seen in movies like "District 9".

Care of babies: As Amadeus said, they could be socialists like chicken (I think chickens cares for eachother chicks?) but for much shorter time, because they don't have neocortex so no need to teach them anything. Like lizards, they are just a miniture of the adults.

Mating: They could lay unfertil eggs, and wait for other "females" to spray them with love, like fish do. Both parents are females, females have both sex organs. They could theoretically fertilize their own eggs but evolution drove them away from this behaviour because it produces clones or defected offsprings.

Feeding: They could have roles like bees, but lets say who ever not attending to offsprings goes out to bring food. They also returns an arm or a leg for their tribe/colony to feed theose who can't, they recepricate in this manner just like bats do.

Problem: Flying animals always have super optimized body structure to produce as light weight as possible even sacrificing brain power for the sake of being light, and they have a reason to fly (migration etc). I don't think it is easy to carry 50kg with skin wings. Unless they can also jump really high to asssist short flights if the reason was to retreat until the next meal.

  • $\begingroup$ Thanks. Possibly a different wing design, like feathered, then? $\endgroup$ Jul 17, 2017 at 10:16
  • $\begingroup$ @Calllack There is a bird (historical) that weighted above 80Kg with feather wings en.wikipedia.org/wiki/Argentavis, the problem with his wings is that it can be a turn off if the flying ladies were dependent on attracting men. But who knows anything can happen after a long dry spell :) $\endgroup$
    – Aus
    Jul 17, 2017 at 10:45

I'd correct the "one every two days" flaw, it is implausible: or change it to some component of the body: one brain, one heart whatever.

The solution to your problem is socialism within the species. They care for each other when pregnant, for as long as it takes, and care for their young together, until they are mature. You can shorten the pregnancy to something like ten weeks (a large dog is 9 or 10 weeks).

To prevent cloning; have the females mate: In humans, a female has two X chromosomes, typically one from their father and one from their mother. Same deal, two women, each with two X chromosomes, could only produce a female, with one X from one woman, and another X from the other. How they mate is up to you, as long as they can mix DNA. Offhand I'd make them (unlike humans) able to extract partner DNA from saliva; so if they wish they can become pregnant by simple kissing; or put a biological opening under their tongue that can produce a (molecule sized) egg, or accept one.

The socialism aspect: While one female is pregnant, others bring her food (male brains or whatever). When she has a child, they all care for it equally. Make their social group something like 13 of them; like a witch's coven, that take turns being pregnant, working in childcare, etc. Traveling to foreign cities, if need be they can be guests of a local coven, providing food in exchange for friendly and understanding shelter (along with alibis and reinforcements as needed).

Being brutal against humans does not preclude them being loving and generous, even self-sacrificing, to their own kind.


How about parasitic "embryos"?

They would work a bit like pollen : this species being single-gendered could fertilize itself (like some plants do) and emit "embryos" that need a specific environment to grow. The corpse of a freshly killed human could be a nice environment for the embryo(s) to feed and grow on.

You could even plant embryos on living humans, maybe on males by using seduction or even sex and the embryo could be a sexually transmitted parasite.


For pregnancy we already have Parthenogenesis

Parthenogenesis... ...is a natural form of asexual reproduction in which growth and development of embryos occur without fertilization. In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants parthenogenesis is a component process of apomixis.

Perhaps they lay eggs in the remains of the male they ate (assuming they don't eat the entire remains). Or if you want to go for the more horror vibe, they lay them in a still living male where the eggs hatch and consume the still living host from the inside.

Then, you would have to have the young feed on something other than humans during their growth cycle since they would be too small and lack the attributes to hunt humans. Maybe they only consume humans when they are old enough for reproduction. An example would be mosquitoes. They have carnivorous larva that live is still water. They only suck blood after they mature and are ready to reproduce.


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