somewhat similar to those of the Siricidae, but are much smaller, ranging from only 
about 8 to 14 mm in length. As far as known, the larvae are all parasitic on 
woodborers. 
Superfamily Cephoidea—Family Cephidae 
Stem Sawflies 
The larvae of all members of this family and superfamily are borers in the stems 
of plants such as grasses or berries, or in the tender shoots of trees and shrubs. Only 
12 species are recorded from the United States and Canada. Adults are slender- 
bodied and seldom more than 18 mm long. The body is black or dark colored, 
occasionally marked with narrow yellow bands. The antennae are filiform, with 20 
to 30 segments, and are either spindle-shaped or club-shaped. The front tibia has a 
single apical spur, cleft at the apex. 
The willow shoot sawfly, Janus abbreviatus (Say), occurs in southern Canada 
west to Manitoba and South Dakota, and over much of Eastern United States 
(1136). Its hosts are willow and poplar. Full-grown larvae are white, cylindrical, 
and about 12 mm long. The thoracic legs are indistinctly jointed and fleshy. There 
is a single pair of small prolegs on the last abdominal segment and a short, tubular 
prong on the tip of the abdomen. Adults appear in late May and June and the 
females deposit their eggs in punctures in the shoots of their hosts. Sometimes they 
girdle and weaken the shoots above the oviposition site. The larvae feed by boring 
down through the pith, which kills the shoot for varying distances. Winter is spent 
within the shoot in cocoonlike structures. There is one generation in the North, and 
three generations in Mississippi (//36). 
Suborder Apocrita 
Members of the suborder Apocrita have the base of the abdomen constricted into 
a slender petiole or “‘waist.”’ The constricted portion is the first abdominal seg- 
ment, which is fused to the thorax. Thus, what appears to be the first segment of the 
abdomen is actually the second. The adult female is equipped with a piercing 
ovipositor. In some species it is used as a tool for boring deep holes into the wood in 
which eggs are deposited: other species use it for thrusting eggs into the bodies of 
other insects; in still others, it is connected to poison glands and is used as a Sting. 
The larvae are usually grublike or maggotlike. Some feed as parasites or predators 
on other insects and some feed on plants. Adults feed chiefly on flowers, sap, or 
other plant materials: some parasitic species feed occasionally on body fluids of the 
host. 
Considered as a whole, members of this suborder are far more beneficial than 
harmful. Only a few species are harmful to trees or wood products. A number of 
species are injurious to tree seed and cone crops. Some species of ants are 
destructive to young trees in nurseries, plantations, and natural regeneration areas, 
whereas others are destructive to finished wood products. At present, there are 
approximately 15 times more species in this suborder than in the Symphyta. 
Superfamily Ichneumonoidea 
This superfamily constitutes one of the largest groups of parasitic insects (more 
than 5,000 species) and from the point of view of effectiveness in holding in check 
the numerous pests that infest plants, it probably ranks first (2/6). It comprises five 
families (Stephanidae, Aphidiidae, Braconidae, Hybrizontidae, and Ich- 
neumonidae), containing more than 30 subfamilies, hundreds of genera, and thou- 
sands of species (697). Only a small portion of the important species parasitic on 
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