By Susan Milius
Evading predators may be the big factor driving certain caterpillars to shoot their waste pellets great distances.
Caterpillars of the silver-spotted skipper (Epargyreus clarus) can fire their feces as far as 153 centimeters, reports Martha R. Weiss of Georgetown University in Washington, D.C. Accounts from other researchers record tales of shots by caterpillars of other species of up to a meter.
To compare three theories of what evolutionary force drove the development of such firepower, Weiss set up challenges for groups of silver-spotted skippers, a species in which a caterpillar builds a series of shelters out of curled leaves and silk lines as it grows.