HYMENOPTERA 



903 



belong all of the Chalastogastra in which the radial cross-vein of the 

 fore wings is opposite cell R4, or cell R3, or is wanting, except, the 

 small family Cimbicidse. The typical sawflies differ from the Cimbi- 

 cidas in lacking pleural sclerites in the abdomen and in that the 

 antennas are not clavate. The anterior tibiae and tarsi do not bear 

 ribbon-shaped or spatulate hairs, as in the Cimbicidae ; and the pulvilli 

 are inserted on the end of the last tarsal segment and are retractile, 

 like the finger of a glove. The sheath of the ovipositor extends but 

 little if at all beyond the end of the abdomen. 



The larvas are caterpillar-like; the thoracic legs are always present 

 and are usually well developed, but are vestigial in some species. 

 Prolegs are usually present; these are borne on abdominal segments 

 2-7 and ID or 2-8 and 10, rarely the prclegs are vestigial. The larvae 

 of the different species differ 

 greatly in size, varying from 

 10-40 mm. in length. 



The larvae of the majori- 

 ty of the species live free on 

 the foliage of plants, upon 

 which they feed (Fig. 1 1 4 1 ) . 

 The plants infested by the 

 different species include 

 trees, both deciduous and 

 conifers, shrubs, herbs, 

 grasses, and ferns. The lar- 

 vae of some species are leaf- 

 miners; others fold the 

 edges of leaves ; some make 

 galls on leaves, especially of 

 willow and poplar; others 

 make galls in the stems of 

 these plants; and one spe- 

 cies, Caulocampa acericau- 

 lis, bores in the petioles of 

 maple leaves. Among the 

 species that have attracted 

 attention on account of their 

 economic importance are the 

 following. 



The imported currant- 

 worm, Pteronidea ribesi: — 

 This is the commonest and 

 best-known of the garden pests. The adult sawflies appear early in 

 the spring and the females lay their eggs in rows along the principal 

 veins on the underside of the leaves of currants and gooseberries. 

 The eggs are glued to the leaf -veins and not inserted in slits, as is 

 usually the case with sawflies, and they increase considerably in size 

 before hatching. They hatch in a week or ten daj^s; and the larvae 

 begin at once to feed upon the leaves. Often by the time the larvae 



Fig. 1 1 41. — The locust saw-fly, Pteronidea 

 trilineata: a, egg; b, young larva; c, full- 

 grown larva; d, anal segment of full-grown 

 larva; e, cocoon;/, adult. 



