Corn Earworm

The corn earworm, Helicoverpa zea, is a serious pest of field crops and vegetables in Maryland. In late summer, adult earworm moths shift their attention from fields of drying corn and start laying eggs in soybeans, where they can cause serious economic losses. The pupal stage of corn earworm goes virtually unchallenged by natural enemies in this area.

The Plant Protection Section is attempting to introduce a new parasite, Ichneumon promissorius, an exotic species that attacks earworm pupae. This parasite is from Australia where it parasitizes over 20% of a closely related species of earworm. Since 1999, over 23,000 I. promissorius have been released in Maryland. More releases are scheduled for 2003.

I. promissorius were recovered from field-collected pupae for the first time in 2002, indicating successful field parasitism. We will also survey for overwintering parasites to see if establishment has begun to occur. This project is funded in part by the Maryland Soybean Board and the Maryland Grain Producers Utilization Board. 

Ichneumon promissorius
parasitizing a corn earworm pupa.
(photo by Gaye L. Williams, MDA)