About Heterostylum robustum (Osten Sacken, 1877)
Heterostylum robustum is a species of bee fly in the family Bombyliidae. This species occurs in southwestern Canada, most of the western United States, and Mexico. This insect acts as a parasite that attacks bees and wasps by launching its eggs into their host nests. It is the main parasite of the alkali bee Nomia melanderi, which is an important pollinator of alfalfa in the U.S. states of Washington, Oregon, Idaho, and Wyoming. Additional recorded hosts of Heterostylum robustum include several species of solitary bees: Nomia nevadensis bakeri, Dieunomia triangulifera, Calliopsis anthidia, Nomia scutellaris, and Halictus rubicundus.
