Malacosoma californica “Western Tent Caterpillar Moth” Lasiocampidae

Clinton, MT
July 25, 2015
Robert Niese

Tent caterpillar moths were some of our most abundant visitors during our Mothlighting event for National Moth Week with the Missoula Butterfly House. They are positively adorable as adults, wouldn’t you agree? In our area, we tend to have mostly Western Tent Caterpillars, but we do also get Forest Tent Caterpillars (M. disstria). Caterpillars of M. disstria tend to have broader blue dorsal bands, keyhole-shaped white dorsal spots, and whiter tufts of lateral hairs than M. californica, which, in our area, tend to have more yellow than blue

(however, farther east they tend to lack yellow entirely)

and tend to have dash-shaped white dorsal spots. Adults are far more difficult to distinguish, but in general, M. californica tends to have two lighter-colored lateral bands on its forewings in addition to dark bands, while M disstria tends to lack these bands and only has dark bands. But from the underside, they all just look like teddy bears.