The impact of ground cover characteristics on the subsurface pupation and survival of Lepidoptera in urban ecosystems

North American caterpillars predominately feed on tree hosts, and subsurface pupation among arboreal Lepidoptera is widespread. Therefore, such species are vulnerable to the microhabitat conditions near the base of host trees during wandering and subsequent pupation. This susceptibility may help explain recent declines in Lepidopteran diversity and abundance, especially in urban environments. I hypothesize that ground cover characteristics impact wandering behavior and overwintering survival due to cover-type-associated changes in soil compaction, moisture, litter depth, and canopy cover. In preliminary investigations, five species of caterpillars were observed during the wandering stage on six distinct ground covers. Overall, average substrate compactions beneath tree canopies were negatively correlated with the burrowing rate of all focal species combined (# of burrowing successes/ # of attempts, n = 123). Individuals were significantly less likely to burrow within an hour and a half at sites with higher compaction. Additionally, surveys of landscape practices via Google Earth show that turfgrass is the dominant ground cover of choice under landscaped trees in front yards east of the Mississippi. Overwintering survival and ground cover choice tests are underway to further investigate factors that impact survival and larval navigation of urban environments.