72 
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 7. gigantea, which is bred from 
the large globular galls produced on stems of golden-rod by a fly (T'rypeta solid- 
aginis), about the size of a house fly, with mottled wings. 
The closely allied genus Isosoma contains species which depart from the para- 
sitic habits of the majority of the family, and become themselves noxious insects. 
LIsosomu 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 Pteromalinz 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 rape) and 
of Vanessa antiopa. I have counted 
Fic. 40. 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 7. eswrws (Fig. 42) has been bred from the cotton moth, 
The genus Trichogramma (which constitutes a sub-family) also has similar habits, 
and 7. minutum (Fig. 41) is a parasite of our 
large Milkweed Butterfly (Danais archippus). orn, 
PROCTOTRUPIDE—This family has been but ¥%= as 
meagrely investigated in Canada, although the  “*=i+"Z 
species are numerous, and often of interesting a9.“ 
ae : Dp a 
structure. They are not so varied in coloring as TTT 
the Chalcidide, to which they are closely related, R® 
but are usually brown or black. Many of them Rain A Xt 
are wingless, living among low herbage and moss, ¢ 
and some of the genera consist of species so Fic. 41. 
minute that they live and mature in the eggs of 
other insects. I have found clusters of moths’ eggs from each of which, instead of 
a young caterpillar, has issued a perfect winged 
fly (Teleas orgyiw.) Those of Scelio infest, I 
believe, the eggs of grasshoppers or crickets. 
PELECINIDZ—This family is a very easy one 
to study, as it contains only one species, Pelecimus 
polyturator, the shape of which is so different. 
from all other hymenoptera that it can be quickly 
recognized. This fine insect is of a glossy black, 
with short wings, containing few veins. The male 
has a club-shaped abdomen, but the female has hers 
greatly elongated—about five times the length of 
her head and thorax—her total length is about two inches. The females are 
