ae in this country are those which destroy the seeds of their 
osts. 
Chalcids are mostly small to minute in size—some are less than 
one-fourth of a millimeter in length. The antenna is elbowed, the 
pronotum does not extend back to the tegula; the trochanter is 
two-jointed; the forewing is without either a stigma or closed 
cells, and the ovipositor issues some distance before the apex of 
the abdomen. 
FAMILY MYMARIDAE 
This family is represented by more than 100 species in the 
United States and Canada, the majority of which occur in the 
east. All members of the family are internal parasites in the eggs 
of other insects, particularly of Homoptera. Adults are mostly 
black or yellowish in color and are extremely minute in size, 
usually less than 1 mm. long. 
Polynema striaticorne Gir. is an important parasite of several 
species of membracids. It also attacks various aphids and other 
insects. Balduf (30) discussed its bionomics in Ohio and Illinois. 
Acmopolynema bifasciatipennis bifasciatipennis (Girault) para- 
sitizes the eggs of several species of tree crickets. Ooctonus aphro- 
phora Milliron attacks the Saratoga spittlebug. 
FAMILY TRICHOGRAMMATIDAE 
The family Trichogrammatidae consists of extremely small in- 
sects all of which are internal parasites in the eggs of other in- 
sects. Hosts have been recorded from the orders Lepidoptera, 
Coleoptera, Hymenoptera, Neuroptera, Diptera, and Hemiptera, 
but the Lepidoptera are preferred. Muesebeck, et al. (550) list 40 
species as occurring in the United States and Canada. 
Trichogramma minutum Riley parasitizes the eggs of a great 
many species of insects, including many important enemies of 
trees. The following is only a partial list of important eastern 
hosts: locust leaf miner, gypsy moth, brown-tail moth, orange- 
striped oak worm, the saddled prominent, walnut caterpillar, 
satin moth, hickory shuckworm, European pine shoot moth, Nan- 
tucket pine tip moth, forest tent caterpillar, spruce budworm (as 
many as 75 percent of spruce budworm eggs may be attacked), 
black-headed budworm, bagworm, elm sawfly, fall webworm, 
yellow-headed spruce sawfly, and the fall cankerworm (588). 
The adult is less than 14 mm. long, and it inserts its eggs 
directly into host eggs. During warm weather, the life cycle may 
be completed within 9 to 16 days and there may be a dozen or 
more generations per year. 
FAMILY EULOPHIDAE 
Adults of this family are very small, ranging in length from 1 
to 3 mm. Well over 100 species are known to parasitize tree- 
infesting insects, several of which are important pests (588). A 
number of foreign species have been imported into the United 
States and Canada in efforts to control several species of intro- 
duced pests. 
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