900 



AN INTRODUCTION TO ENTOMOLOGY 



change to the pupa state takes place in April and the adult emerges 

 in May. The obvious method of control of this pest is to remove 

 and bum the infested portion of the canes while the larvae are in them. 



Fig. 1 140. — Cimhex americana. Abdomen 

 except first segment: 7, 8, g, pleurites; 

 T, T, T, tergites; S, S, S, sternites; cr, 

 cercus; sp, spiracle. (After Snodgrass.) 



Family CIMBICID^ 



The Cimbicid Sawflies 



This is a small family, which is represented in our fauna by a 

 few genera and a limited ntunber of species. In this family the body 



is stout and often very large; 

 there are distinct pleural scler- 

 ites in the abdomen (Fig. 1 140) 

 and the antennse are clavate. 

 The anterior tibias and meta- 

 tarsi bear ribbon-shaped or 

 spatulate hairs ; the pul villi are 

 large, broadly sessile on the 

 last tarsal segment, and are 

 not retractile. The sheath of 

 the ovipositor extends but lit- 

 tle if at all beyond the end of 

 the abdomen. 



The body of the larvae is cylindrical, stout, and covered with a 

 waxy bloom when living; the thoracic legs are well-developed and 

 five-jointed; and the abdomen bears eight pairs of prolegs. The lar- 

 vae live free upon foliage upon which they feed. 



The American sawfly, Ctmhex americana. — This is the largest of 

 our common sawflies. The female is about 1 8 mm. in length and has a 

 black head and thorax, a steel-blue or purplish abdomen, with four yel- 

 lowish spots on each side, smoky brown wings, and black legs, while her 

 feet and short, knobbed antennee are pale yellow. The male is longer 

 and slenderer and differs somewhat in color. Several varieties of this 

 species, differing in color, have been described. The eggs are laid in 

 June in crescent-shaped slits made in leaves. The food plants are elm, 

 birch, linden, and willow. The larva is greenish yellow, with black 

 spiracles and a black stripe down its back. When disturbed it spurts 

 forth a fluid from glands just above the spiracles. It clings to the 

 upper surface of a leaf and feeds on the edge of the leaf. When not 

 feeding it rests on one side with the body curled up in a spiral form. 

 There is but one generation each year. When the larva is full-grown 

 it burrows in the ground, makes an oval, brownish cocoon, and there 

 spends the winter, not changing to a pupa until spring. The adults 

 appear in May or June. 



Family TENTHREDINID^ 



The Typical Sawflies 



This is a very large family, including more than seven-eighths of 

 all of the members of the suborder Chalastogastra. To this family 



