Notes on the biology of Diglyphus intermedius (Hymenoptera: Eulophidae), a parasite of the alfalfa blotch leafminer, Agromyza frontella (Diptera: Agromyzidae).
The biology of Diglyphus intermedius (Gir.), the commonest parasite of Agromyza frontella (Rond.) on lucerne in Delaware, south-central Pennsylvania and southern New Jersey, is described from observations in the laboratory on the eulophid parasitising Liriomyza trifoliearum Spencer, and in the field in Delaware, Pennsylvania and New Jersey on A. frontella and Liriomyza spp. on lucerne in 1975. D. intermedius accounted for almost half the 18.8% parasitism in A. frontella in the field, and the final (third) larval instar was preferred. The ectoparasitic larvae were usually solitary, but up to 5 parasites occasionally developed on a single host. Adult females attacked and paralysed or killed host larvae in all 3 instars. There were 3 larval instars (as indicated by changes in mandible length). Development took 11 days at 25.5 deg C, and adults lived for 3-4 weeks, the fecundity averaging 40 offspring/female.