Cockroaches Get Lonely, Kind of (But a Little Feather-Poking Can Help)

By Sarah Zhang | May 3, 2012 4:07 pm


When people think of cockroaches, some may think of the much-smarter-than-a-bug Gregor Samsa, but it takes a special kind of person—a social biologist, really—to think of them as “gregarious.” Yes, these unloved (by humans), trash-eating creatures have social lives too. A recent review in the journal Insectes Sociaux highlights the social behavior of two so-called gregarious cockroach species: Blattella germanica and Periplaneta americana. Although not as sophisticated as eusocial insects like ants or bees, these cockroaches can communicate, recognize kin, and even get “lonely” in isolation. Now we’re getting Kafka-esque.

To talk to and recognize one another, cockroaches use hydrocarbons, molecules that are made of only hydrogen and carbon atoms. These chemical markings help them identify group shelter spots, where they hang out together during the day between nightly foraging runs. (When they are out looking for new shelter or food, they tend to follow the crowd too.) The hydrocarbon signature is unique to each cockroach. Siblings can recognize each other and avoid incest, which is not so great for genetic diversity.

When forced into isolation by lab researchers, these gregarious cockroaches get “isolation syndrome,” taking longer to molt and reach sexual maturity. Isolated cockroaches also have problems courting mates, which hints at the possibility that they learn these sexual behaviors through social contact. That may sound familiar to us humans, but let’s not dive too far into anthropomorphism here. The review’s authors suggest that for cockroaches, social contact is quite literal: in their normal group-living environment, cockroaches crawl all over each other, and it’s this physical contact—much of which can be replaced by a stimulus as simple as poking with a feather—that stimulates their physical development. Group living also keeps them warmer and minimizes water loss.

The social life of the gregarious cockroach is not as sophisticated as a human or even an ant, but it knows better than to go it alone.

*We know, we know: Kafka never actually specifies that Samsa was turned into a cockroach—the original text reads “insect”—but the fact that The Metamorphosis has become connected to cockroaches in the popular imagination says something about the buggers, right? Incidentally, novelist (and noted butterfly expert) Vladimir Nabokov insisted that Samsa was turned into a beetle. He even sketched it out

[via BBC]

Image via Wikimedia Commons

  • Rich

    I raise Madagascar hissing cockroaches as a hobby and yes, they are indeed social creatures. This is most obvious when they jostle for position on their logs and establish little territories and pecking orders and such. Having spent countless hours observing them, I would also agree that an isolated roach would be an unhappy roach but for the life of me I can’t imagine why anyone would spend money to figure that out.

  • floodmouse

    This reminds me of the recent story in Discover magazine about the unlicked rats. (If the mom rat doesn’t lick the babies enough, they grow up timid and have trouble adapting to new situations.) Interesting that this syndrome goes beyond mammals. How deeply is it hardwired into the DNA?

  • Maureen Murchison

    Darn … now you have me feeling sorry for the poor lonely cockroach. I already knew a lot about rats as I had a pet one when I was a child … until my mother realized it wasn’t a cute mouse.

  • John Lerch

    Hmm, as I recall the description Kafka gave was of a beetle.

  • marcel

    Us lowbrow types think not of Gregor Samsa but of Archy

  • Clayton

    I’ve observed roaches outside in the same place every night when walking my dogs. After a few weeks I began to ask why they were always in the same spot? So I began watching them for longer and longer spans of time. After watching them for several cumulative hours they did indeed have social behaviors (i thought). Wing flapping and antennae brushing was common upon one roach approaching another. I also noticed that if one got smashed by an earlier walker the roaches would crowd around the dead insect. I thought it may be for them to feed on it, but after this article who knows…interesting!


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