Host plant associations among species in two macrolepidopteran assemblages

Host plant associations of macrolepidopteran species in assemblages on box elder, Acer negundo L., and black willow, Salix nigra (Marsh), were characterized. Almost 90% of the macrolepidoptera collected on these two riparian tree species of the mid-Atlantic area of the United States were new host records. Larvae of 87 species (and another nine specimens identified to genus) were collected on box elder and black willow. About one-fifth of the species were found exclusively on box elder, one-third exclusively on black willow, and about one-half of the macrolepidopteran species were found on both tree species. Although many macrolepidoptera were found on both tree species, they were not equally abundant on both trees, suggesting a predominantly favored tree species. However, there was no statistically significant asymmetry in host tree species use.