Malacosoma sp. “Tent Moth” Lasiocampidae, pupa on
Larix occidentalis “Western Larch” Pinaceae

Apgar Lookout Trail, Glacier National Park, MT
October 9, 2015
Robert Niese

The trails around Apgar are rife with Lasiocampidae pupae. They’ve spun their webby cocoons in every manner of tree, shrub, and man-made structure. Around Missoula, it wasn’t a very big year for tent moth caterpillars, but only a hundred miles away in Glacier National Park, Malacosoma numbers were significantly higher. These species go through regular boom and bust cycles and some years they become so abundant that entire forests can get defoliated. In my search of the literature, it appears that these moths overwinter as eggs, not as pupae. These pupating individuals certainly won’t survive the oncoming cold if that is indeed the case.

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