Gypsy Moth Caterpillar
Long hairs on caterpillars are presumed to be defensive. How well do they defend against insect predators? Sugiura and Yamazaki* observed attacks by the predatory carabid beetle Calosoma maximowiczi
, on several species of caterpillar. Smooth caterpillars with no hairs were successfully attacked and captured on the first attempt. Gypsy moth larvae, which have long hairs, were successfully attacked and captured, but only after multiple attempts. Tiger moth larvae with hairs longer than the madible length of the carabid beetle were successfully captured by fewer than half the beetles observed. Trimming the hairs on the caterpillar increased predation success to 100 percent.
Caterpillar hairs must be sufficiently long to effectively prevent capture by predatory beetles. Hair does provide some protection delaying capture and perhaps allowing time for the caterpillar to escape by leaving the area.
*Shinji Sugiura and Kazuo Yamazaki. 2014. Caterpillar hair as a physical barrier against invertebrate predators. Behavioral Ecology, online