Nest aggregations of the solitary bee Ptilothrix bombiformis (Cresson) (Hymenoptera: Apidae, Emphorini) in lawns of suburban residences and parks

Nesting biology and nest architecture have been described previously for populations of Ptilothrix bombiformis (Cresson) (Hymenoptera: Apidae, Emphorini) in the wild. Current research in bee ecology has begun to examine bees in urban and suburban habitats in order to determine the impact that habitat modification by humans has on bee populations and to understand which species contribute to pollination of plants in these man-made habitats. This study describes two nest aggregation sites in suburban residential habitats, one in Kentucky and the other in Kansas. The conditions for both nest aggregations were very similar. Both were in patches of bare clay soil within expanses of mowed grass, contained approximately 25 total nests and had approximately six females actively nesting at a given time. Nests were only in bare soil, none were found in areas fully covered with grass. The site in Frankfort Kentucky was in a soccer field actively used by children’s soccer league in a city park. This aggregation was stable during three years of observation. The other aggregation was in a residential lawn in Pittsburg Kansas. This population apparently was only active at that site for one year. No bees emerged from two nests in a block of soil that was excavated for study. An unknown parasite emerged from both nests. The following year there were no nests active in the lawn. It is unknown if they were killed by parasites, emerged and moved, or were killed by pesticides.