In mid-September 1974, adults of Ichneumon canadensis Cress, emerged in the laboratory from pupae from the soil under field cages at Grosse Isle, about 15 miles northwest of Winnipeg, Man. The field cages had been stocked with laboratory-reared fifth-instar larvae of M. configurata. The cages were removed after 12–15 days when the larvae had finished feeding. Eleven I. canadensis emerged from 1671 pupae collected from experiments set up on 29 July, 2 August, and 12 August; none emerged from 229 pupae collected from experiments set up on 17 and 22 July. Parasitization could have been by adults that either were trapped inside the cages when they were erected, or that emerged later from the soil inside the cages, or that discovered the host-containing area after the cages were removed but before the soil was sifted. As this was the first report of this ichneumonid parasitizing M. configurata, various aspects of the parasite's biology were investigated.