Shoot the poop
Some caterpillars get rid of their waste with ballistic force.

This silver spotted skipper caterpillar was photographed in the Julie Metz Wetlands of Woodbridge, Va.
JUDY GALLAGHER/WIKIMEDIA COMMONS (CC BY 2.0)
This silver spotted skipper caterpillar was photographed in the Julie Metz Wetlands of Woodbridge, Va.
JUDY GALLAGHER/WIKIMEDIA COMMONS (CC BY 2.0)