How to Manage Pests
Identification: Natural Enemies Gallery
Elm leaf beetle parasite
Scientific name: Erynniopsis antennata
DESCRIPTION Life Cycle
This fly is the most important parasite of elm leaf beetle in California. Adults are small, black, robust, and hairy. They look like houseflies, except that they are smaller, about 3/16 inch (4 mm) long, and have stout bristles at the tips of their abdomens. Metamorphosis is complete. The female fly deposits one egg on a late-instar beetle larva. After hatching, the larva enters its host and feeds and pupates inside. Black to reddish, cylinder or teardrop shaped pupae occur during spring and summer at the base of trees among the yellowish beetle pupae. The tachinid pupae are sometimes attacked and killed by a wasp or secondary parasite (hyperparasite), Oomyzus erynniae.
As the season progresses, an increasing proportion of the parasite population enters diapause. Each overwintering Erynniopsis remains as an immature parasite within its host during the beetle's pupal through adult stages. In the spring the Erynniopsis antennata adult fly emerges from the adult beetle, although this is not readily observed.