Cockroaches Eat Each Other After Sex and Here's Why

Yes, cockroaches take turns eating parts of each other in a display of post-sex cannibalism.
Chris Young

The natural world is a place of diversity, awe-inspiring beauty, wonder, and also cannibalistic cockroaches that eat their partner's wings after fulfilling their carnal desires.

Yes, you read that right — cockroaches take turns eating parts of each other after mating in a display of post-sex cannibalism. 

Now, a study led by Haruka Osaki, a student at Kyushu University in Japan, sheds light on the reasons behind the bizarre post-coital behavior.

The researchers behind the study filmed 24 pairs of mating cockroaches (Salganea taiwanensis) that subsequently ate each other's wings for days on end.

The practice seems to be common, ScienceAlert explains, as 99 percent of roach parents appear to display chewed stumps where their wings use to be located.

In half of the couples filmed, the bizarre behavior would continue until all four wings were completely gone. On a third of occasions, however, the recipient "violently shook its body left and right", which would sometimes get the mate to stop eating.

Cockroaches might display conflict-free sexual cannibalism

Though sexual cannibalism, and other forms of cannibalism, aren't unheard of in the animal kingdom, reciprocal feeding is a unique behavior to cockroaches.

The researchers say that cannibalistic behavior might actually have more to do with grooming than feeding, as both roach wings are not made of actual flesh and they would provide little nutritional value.

Cockroaches Eat Each Other After Sex and Here's Why
A drawing showing cockroach mutual wing-eating behavior, Source: Haruka Osaki

In fact, the study authors suggest that the specific type of wood roach observed might display this behavior to increase its partner's chances of survival. After finding a mate, wood-eating roaches feed and protect their young inside a rotting log which they make their home.

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The parent roaches share the parenting load in cramped living quarters where wings aren't all that useful. The wings also leave the roaches vulnerable to infection, mites, and other roaches looking for a mate.

The act makes parenting easier as it allows the roaches to navigate the inside of their log with greater ease. What's more, not being able to fly isn't a great hindrance to adult roaches, as the wood-eating insects have all the food they need in their log homes.

In other words, the researchers suggest that eating one another's wings after sex might be an act of loving kindness bestowed from one roach to another.

So cockroach cannibalism might actually be one of the natural world's more heartwarming behavioral displays — but thinking about it is still going to give us nightmares.

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