Insects such as roaches, house flies and carpenter ants often engage in an antennae-grooming behavior which label them as "clean" insects, but it's the cockroach that gets most of the credits.
To figure out just why roaches groom, lead author Katalin Böröczky and colleagues from North Carolina State University along with researchers from the Russian Academy of Sciences observed antennae-cleaning behaviors in a couple dozen adult male American cockroaches.
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.
The researchers guessed that this build up might impair the roaches’ ability to sniff out olfactory signals with their antennae.
To test this hypothesis, they exposed roaches with groomed and ungroomed antennae to sex pheromones and other odors. Just as they suspected, roaches with clean antennae were more receptive to the odors around them than those with unclean ones.
For more info, see SmithsonianMag.com - Why Cockroaches Meticulously Groom Their Antennae.