Why Do Bugs Turn Over on Their Backs When They Die?


Bug image via Shutterstock

It doesn’t happen to every single bug, but if you stumble upon an expired roach in the bathroom or a downed fly by the window, you’ll find that they’re frequently flat on their backs, legs in the air. It’s such a familiar death pose that it’s omnipresent in a Google image search and name-checked in an ab exercise.

One reason this happens so often is the way in which most bugs in our homes meet their untimely end: poison. Insecticides usually work by disrupting nerve impulses and shutting down communication in a bug’s nervous system. In a one-two punch, the poison ravages a bug’s coordination and also causes spasms and convulsions. Once a bug stumbles and lands on its back or spasms so hard that it flips itself over, it usually can’t handle the intricacies of righting itself again. There it’s stuck until death takes hold.

Even without a blast of bug spray to nudge it off this mortal coil, dead or dying bugs often land on their backside simply because of their small size. A stiff breeze, a human rushing by or a curious pet are all enough flip a tiny corpse, or an injured bug too weak to flip itself back over.