[2] The two species look almost identical to one another; however, they can be distinguished morphologically by comparing uncus shape or by using DNA analyses.

The neonates primarily feed on the buds and nearly unfurled leaves of sugar maple, American beech and trembling aspen.

After feeding for a few weeks, the late instar caterpillars drop down to the soil and build an earthen cocoon.

Disease from viruses and microsporidia have been noted to effect the larvae and pupae of the Bruce spanworm.

[5] However, collections for Bruce spanworm larvae from an outbreak population in Maine had high levels of infection by microsporidia.