. Annual report - Entomological Society of Ontario. Entomological Society of Ontario; Insect pests; Insects. The genus Torymus contains a number of species, which may be bred from different galls. The females have the abdomen flattened ovate, and sometimes prolonged to an acute point; the abdomen of the males is very small, and the insects are black. A not uncommon species is T. gigantea, which is bred from the large globular galls produced on stems of golden-rod by a fly (Trypeta solid- aginis), about the size of a house fly, with mottled wrings. The closel}^ allied genus Isosoma contains spe
. Annual report - Entomological Society of Ontario. Entomological Society of Ontario; Insect pests; Insects. The genus Torymus contains a number of species, which may be bred from different galls. The females have the abdomen flattened ovate, and sometimes prolonged to an acute point; the abdomen of the males is very small, and the insects are black. A not uncommon species is T. gigantea, which is bred from the large globular galls produced on stems of golden-rod by a fly (Trypeta solid- aginis), about the size of a house fly, with mottled wrings. The closel}^ allied genus Isosoma contains species which depart from the para- sitic habits of the majority of the family, and become themselves noxious insects. Isosoma hordei (Fig. 40) is the well-known Joint-worm of wheat and barley straw, making gall-like swellings at the joints, in which several cells may be found, each, containing a little grub. The sub-family Pteromalinse contains, amid a great complex of tribes and genera, a correspondingly great number of species. The typical genus, Pteromalus, alone con- tains more than 30 species, of which some are well-known parasites of butterflies. P. puparum is recorded as bred from eleven species of butterfly, and is a com- mon destroyer of the chrysalids of the cabbage white butterfly {Pieris rapce) and of Vanessa antiopa. I have counted more than 450 flies from one pupa of the latter, and sometimes scarcely an unin- fested chrysalid can be found. The species of Tetrastichus are also frequently parasites of butterflies, while T. esurus (Fig. 42) has been bred from the cotton moth^ The genus Trichogramma (which constitutes a sub-family) also has similar habits, and T. minutum (Fig. 41) is a parasite of our large Milkweed Butterfly (Danais archippus). Froctotrupid^.—This family has been but meagrely investigated in Canada, although the species are numerous, and often of interesting structure. They are not so varied in coloring as the Chalcidid^, to which they are closely r
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectinsects, bookyear1872
