BIOSYSTEMATICS OF THE TINGID PARASITE HOLDAWAYELLA IN ONTARIO (HYMENOPTERA: BRACONIDAE, EUPHORINAE)

Holdawayella juglandis Loan, a new species, and some aspects of the anatomy of the final-instar larva of the only other known species of this genus, H. tingiphaga Loan, are described. Host records and field data are reported for both species for Ontario. Though the adults of the two species are very similar morphologically, H. juglandis lacks parthenogenesis, is restricted to the tingid Corythucha juglandis Fitch that breeds only on species of Juglans L., and has specific phenological characteristics. In both species, the head sclerites of the final-instar larva are typically euphorine, and the abdomen bears 3 unpaired, medial, teat-like appendages on segments 5, 6, and 7 whose function is unknown and which do not seem to have homologues in other insect larvae. Both species are single-brooded, lay their eggs in late-instar nymphs and possibly also teneral adults of Corythucha, overwinter as first-instar larvae in adults of these tingids, and complete their endoparasitic and cocoon development in about 90 days during the following spring and summer so that adults of H. tingiphaga begin to emerge from the soil about mid-July and those of H. juglandis about 8 days later. New host records for H. tingiphaga are C. coryli O. & D., C. heidmanni Drake, and C. ulmi O. & D.