Ever Wonder Why Cockroaches Die Upside Down?
Discovery Place Science
Question: Have you ever come back from vacation to be greeted by a cockroach, middle of your kitchen floor, dead as a doornail?
Better question: Ever seen a dead cockroach that wasn't upside-down?
These six-legged pests prefer hot, humid atmospheres, much like our living Rainforest in Discovery Place Science. Because they are attracted to our Rainforest and sometimes make their way inside our Museum in hopes of getting to the humid space, we occasionally find a dead one somewhere in the Museum on its back, having had free reign of the place for a final night. But, is this behavior normal? Do roaches flip around in the wild, or is it something about human dwellings?
There are two main cockroach species found in homes in North Carolina, the German roach (Blattella germanica) and the American roach (Periplaneta americana). German roaches are generally smaller, with parallel lines running from head to wingtip. American roaches are light brown and are a little bigger. Chances are, the ones you see in your house are the German variety since they are more common in living spaces. The terms "water bug" or "palmetto bug" are just colloquial names for these cockroaches (usually referring to the larger American version). Both roach species can fly when they reach adulthood and develop wings, while adolescent roaches are wingless.
Both species, under the right circumstances, will turn belly-up in the kitchen more often than in the bedroom. One reason is the slick flooring, linoleum or polished hardwood. Older, injured, or handicapped roaches might slip and fall on their back and then are unable to right themselves on the near-frictionless surface of your home. Carpet is enough traction to turn over and continue living, the same goes for leaves and debris on the forest floor.
Most likely, the insects were exposed to a toxin sprayed around the house to eliminate these disease vectors on legs. Most bug sprays mess with the roach's internal circuitry, their nervous system. Unable to remain coordinated, staggering around intoxicated, they'll flip over and perish, legs to the sky.
But roaches are notoriously resilient otherwise, being able to withstand radiation levels that would kill a person in 10 minutes. (No, cockroaches cannot survive a nuclear blast, just most of the fallout from it.) This is most likely because of slow cellular processes and small bodies. Chop off a head, and the body can still be alive for up to 10 days because they don't eat a lot and they breathe through their sides, not mouth. They are also very hard to drown, being able to hold their breath for 30 minutes.
Not all roaches shove off this mortal coil facing the sky. In the wild, those that are lucky to live long enough to die of natural causes don't usually hang around to be observed face down but are instead easy prey for scavengers or the elements. It's just a different story inside your home.
Creeped out? Just be glad the largest of the roaches lives only in South America, where it grows up to six inches and has a one-foot wingspan.
Still want more to fill your insect fix? Stop by Bug Lab on your next visit to Discovery Place Science.