You know how dogs sniff each other’s poop to get information on the other guy, what he’s been eating lately, and his general health? Well, cockroaches do the same thing, sort of.

For a long time, entomologists have known that cockroaches possess some kind of aggregation pheromone that attracts them and causes them to group together in a desirable location. The aggregation pheromone says, “Here we all are, and this place is great. Come on in!” Researchers hadn’t been able to isolate those pheromones, however, and couldn’t determine if they were in the cockroaches’ cuticle or fatty bodies, or in their feces.

Scoop! The Pheromone is in the Poop

New research has found that the aggregation pheromones are indeed in the cockroaches’ poop, but not just any poop will do. The poop also has to contain germy bacteria to attract other roaches. A team from North Carolina State University raised German cockroaches in sterile conditions so their poop would be germ-free. They found that most cockroaches were more attracted to poop from their kin that contained bacteria than they were to germ-free poop from the research roaches.

When the researchers tested germ-free roach poop and normal roach poop, they found that germ-free poop also lacked the usual fatty acids that evaporate from poop once it is exposed to air. They concluded that these missing fatty acids were in fact the essence of the cockroach aggregation pheromone.

It’s not too surprising that bacteria would be involved. Insects often partner with different microbes. Bugs are themselves bug-infested. These microbe partners can serve important functions. Cockroach poop needs its bacteria component to attract other roaches to a safe haven where they can find food, shelter, and mates.

Another Reason to Clean Up After Cockroaches

This research brings entomologists that much closer to developing a synthetic aggregation pheromone for cockroaches. That compound could be used to lure roaches to baits, traps, and even insecticides. I think it also means that we should be more careful to clean up the roach “residue” left behind in a heavy infestation. Leaving cockroach poop to accumulate can only serve to attract other roaches to the site.