Why Do Filthy Insects Spend So Much Time Grooming?

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Cats are high-maintenance creatures, as anyone who’s witnessed their fascinatingly persistent grooming routines can attest. (Hairballs are a further testament to the fact.) Such fastidious self-care is reflected in human routines—brushing teeth, combing hair, clipping nails—but also in the habits of scuttling, scream-inducing cockroaches. There’s a certain irony in the hygienic customs of insects whose presence often connotes filth, so why is it that cockroaches devote so much of their creepy-crawly lives to cleanliness?

With antennae that can grow as long as its entire 1.5 to 2-inch body, the American cockroach has plenty of surface area to maintain, which it does by bringing antennae to its mouth with a foreleg and cleaning each segment. Researchers from North Carolina State University explored the function of the insect’s fastidious self-grooming, as well as what kind of muck it was working so ceaselessly to keep at bay. Experiments showed that not only were the roaches removing foreign chemical substances from their antennae, but also excess cuticular hydrocarbons—substances secreted by the creatures themselves to prevent water loss. Other insect species with similar grooming habits—carpenter ants, houseflies, and German cockroaches—also appeared to undertake self-care as a means of regulating cuticular hydrocarbons to a particular level.

By keeping the pores on their antennae open to environmental stimuli, cockroaches are able to “smell” odorants around them, including a sex pheromone compound known to aid them in locating a suitable mate. Just like humans, insects keep it clean for the sake of attracting the opposite sex.

Will this knowledge help tone down the gross-out factor of those tiny household pests? Probably not, but at least you can rest assured that your unwanted guests are trying to stay clean—if only to impress the ladies.