IMPLICATIONS OF TREE MICROHABITAT PREFERENCES OFCOMPSILURA CONCINNATA(DIPTERA: TACHINIDAE) FOR ITS EFFECTIVENESS AS A GYPSY MOTH PARASITOID

Abstract Tethered gypsy moth larvae,Lymantria dispar(L.) (Lepidoptera: Lymantriidae), placed in various tree microhabitats were most heavily parasitized byCompsilura concinnata(Meigen) (Diptera: Tachinidae) near the ground especially on leaves. In laboratory experiments, hosts were parasitized primarily between 6:00 AM and 6:00 PM (E.S.T.), with little parasitism at night. These data suggest that in the field, this tachinid will most efficiently attack young gypsy moth caterpillars, as instars 1 to 3 are the only ones consistently on or near foliage during daylight.C. concinnatafemales successfully parasitized young hosts, but larval development on 2nd instars was twice as long as that on 4th instars. Thus, only one generation of parasitoids on gypsy moths is likely per year. Results indicate that methods for improving the effectiveness of this parasitoid should emphasize increasing adult numbers early in the season.