Systellogaster ovivora Gahan
Natural hosts.—Blatta orientalis, U.S.A., Illinois (Gahan, 1917).
Parcoblatta pensylvanica, Canada, Ontario (Judd, 1955).
Parcoblatta sp., U.S.A., Ohio (Edmunds, 1952a, 1953a).
"Blattid," U.S.A., Maryland (Gahan, 1917).
One oötheca of P. pensylvanica yielded 14 parasites with a sex ratio of 2.5 ♀♀: 1♂ (Judd, 1955). The average number of parasites in 11 oöthecae of Parcoblatta sp. collected in 1950-51 was 27 wasps (Edmunds, 1952a, 1953a). The adults made two to three emergence holes in the oötheca (Edmunds, 1953a; Judd, 1955).
Family EULOPHIDAE
Melittobia chalybii Ashmead
Natural host.—Periplaneta americana, U.S.A., Missouri (Rau, 1940a): M. chalybii is normally a parasite of Coleoptera and Hymenoptera (Peck, 1951). This is the only record from cockroach eggs. Burks (personal communication, 1956) stated that this species will attack any insect to which it is exposed and can be a serious pest in insect cultures of practically any insect order. In nature it seems to prefer the nests of aculeate Hymenoptera; Rau suggested that the parasites were probably brought into his laboratory with mud nests of Sceliphron caementarium (Drury).