By Elizabeth Pennisi
Though often associated with dirty environments, cockroaches are actually quite fastidious, especially when it comes to their antennae. They clean them often by grabbing one in with a front leg and drawing it through their mouth.
Researchers have long observed that many insects groom themselves, and now they know why. When scientists restrained American cockroaches or prevented grooming by gluing mouthparts for 24 hours, they noticed a shiny, waxy buildup on the antennae that clogs the tiny pores that lead to odor-sensing cells.
Measurements of the electrical activity in those cells in response to sex-attractant and food odors showed that the gunk interfered with the roach's sense of smell, they report online today in the Proceedings of the National Academy of Sciences. The insects appear to produce wax continuously, likely to keep from drying out, and grooming helps remove the excess as well as dust and other foreign chemicals that land on the antennae and get trapped in the gunk.
Carpenter ants, houseflies, and German cockroaches also suffered from gunk overload when prohibited from grooming, suggesting that fastidiousness is widespread. See more videos.