INSECT ENEMIES OF EASTERN FORESTS 543 
SuprrraMity THNTHREDINOIDEA 
The Sawflies 
Sawflies are so-called because the female is equipped with an ege- 
laying apparatus, which is a saw in appearance and use. The device is 
composed of three main pieces held within protecting sheaths. The 
upper piece of the saw is a rigid lance with grooves along which the 
other two pieces slide. The last two pieces are the saw blades, or 
lancets, and consist of thin plates with their flat inner surfaces to- 
gether. Each lancet is usually shaped somewhat like a long acute 
triangle, and one long side edge slides along a groove of the lance; 
the other, or lower, long edge is saw-toothed. The exposed outer sur- 
face of each blade has several transverse rows of fine teeth. The nar- 
row base of the triangular lance is the point. from which springs the 
rod that attaches the blade to the abdomen and controls its movements. 
In general, the egg-laying operation consists of forcing or catching 
the lance point in the plant tissue and then pushing one saw lance while 
pulling the other. By this movement the saw is carried through the 
plant tissue and cuts a pocket or slit, in which the egg is laid. Some- 
times the eggs are deposited in definite rows, either with the pockets 
touching at the ends or separated by regular or variable intervals. At 
other times they are scattered about in no apparent order. Frequently 
a definite location, such as the leaf edge or the midrib, is sought for 
oviposition. 
The caterpillarlike larvae are usually naked, although, in a few 
species they are spined, sparsely hairy, or covered with a gummy or 
waxy secretion. Each normally has a single pair of eyes, one on each 
side of the head; three pairs of thoracic legs, usually distinctly seg- 
mented; and various numbers of prolegs. When disturbed, the larvae 
of some species curl themselves up and le on their sides, whereas 
others hold their abdomens aloft over their heads. 
As a group the sawflies are injurious in the larval stage only, and 
they may be gregarious or solitary in habit. Most species live exposed 
and feed on plant foliage, eating the entire leaves or skeletonizing 
them. Some build webbed nests; a few species mine leaves, leaf 
petioles, and twigs; others produce galls on the leaves or shoots of 
willow or poplar; and a few live in catkins, buds, or fruits. 
During the feeding period the larvae grow rapidly and shed their 
skins a number of times. The full-grown larvae either spin cocoons 
or construct. cells in which they transform to pupae and then to 
adults. The cocoons, either single- or double-walled, may be spun on 
the leaves, twigs, and other parts of the host plants, or in the litter or 
earth beneath. Some species make cells in pith, bark, and brashy wood, 
or in the ground. The larvae that live protected within plant tissue, 
sometimes form their cocoons and complete their transformation 
within the mines or cavities made by them. 
The adults frequently resemble small wasps or bees. Many of them 
are slow and not very vigorous fliers. The antennae of sawflies differ 
considerably in the number of joints and may be feathered, clubbed, 
threadlike, forked, or with spurs on some of the joints. 
The life cycle of these insects seldom requires more than a year. 
Certain species may have as many as six generations a year with such 
an overlap of activity after the season is well advanced that all stages 
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