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No abstract

Can. Enr. 109: 137-142 (1977) In the study of insect parasites of the darksided cutworm, Euxoa messoria (Harris), fourth-to seventh-instar larvae were collected from a field at Delhi, Ont., and reared in the laboratory. A total of 701 insect parasites including six species of Hymenoptera and four of Diptera, were reared from the 3970 darksided cutworm larvae collected in 1973 and 1974.Thirteen species of insect parasites of E. messoria are listed. Ten of these species were reared in the present study frornE. messoria in Ontario and all of them are primary and internal parasites. Of the 10, only two have previously been reported as parasites of E. messoria. Host-parasite relationship and the degree of parasitism are given for the 10 species reared in Ontario.

A reliable method for determining the sex of pupae of the dark-sided cutworm is to observe the structures found on the ventral side of the terminal abdominal segments. Two pairs of rounded tubercles, one pair around the genital opening and the other around the anal opening, are present on the terminal abdominal segments of the male, and one pair around the anal opening only on the female.

In the laboratory, the mean number of eggs laid per female of the dark-sided cutworm, Euxoa messoria (Harris), fed on honey solution was 1303.8; when given water alone 261.3; and 86.4 when held without food or water. Adult food significantly increased the longevity and oviposition period and reduced the pre-oviposition period. There was no significant difference between the weight of male and female pupae. The weight of the female pupae was significantly correlated with: the oviposition period; the number of eggs laid; the longevity, except moths fed on honey solution; but not the pre-oviposition period, regardless of food taken as adults. Females fed on honey solution mated successfully, 30% of them more than once. When given water or nothing the number of mated females was reduced. Dissections showed that adult food accelerated the development of eggs and increased the fecundity potential.