HYMENOPTERA 341 



The wheat-sawfly-borer, Cephus pygmceus. — The larvae of this species 

 bore in the stems of wheat, a single larva in a stem, dwarfing and stunt- 

 ing the growth of the plant. As the grain becomes ripe the larva works 

 its way toward the ground ; and at the time of harvest the greater num- 

 ber of them have penetrated the root. Here, in the lowest part of the 

 cavity of the straw, they make preparations for passing the winter, and 

 even for their escape from the straw, as adults, the following year. This 

 is done by cutting the straw circularly on the inside, nearly severing it a 

 short distance from the ground, so that a strong wind will cause it to 

 break off at this point. After the circular cut has been made, the larva 

 fills the cavity of the straw just below it for a short distance with a plug 

 of borings. Between this plug and the lower end of the cavity, the wall 

 of the cavity is lined with silk forming a cocoon within which the larva 

 passes the winter and changes to a pupa in March or April. The adult 

 insects emerge early in May. 



The currant-stem girdler, Janus Integer. — The larva of this species 

 bores in the upper portion of the canes of currant. Its presence is in- 

 dicated by the wilting and drooping, in late spring, of the new growth at 

 the tip of the infested cane. This is due to the fact that the parent saw- 

 fly after depositing her egg in the cane moves up a short distance above 

 where the egg is deposited and with her ovipositor girdles the cane, some- 

 times nearly severing it. This killing of the tip, and thus checking the 

 growth of the cane, seems to be necessary for the development of the egg 

 and larva. The larva bores in the pith of the cane. In the fall it eats a 

 hole through the woody wall of the cane to the outer bark, thus making 

 provision for the escape of the adult, and then spins a cocoon in which it 

 hibernates. The 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 burn the infested portion of the canes while the larva? are in 

 them. 



Family Cimbicid^e 

 The, Cimbicid Saw flies 



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

 genera and a limited number of species. In this family the body is stout 

 and often very large; there are dis- 

 tinct pleural sclerites in the abdomen 

 (Fig. 578) and the antennae are clav- 

 ate. The sheath of the ovipositor 

 extends but little if at all beyond the 

 end of the abdomen. 



The body of the larva is cylin- 

 drical, stout, and covered with a 



wflyv hlnom whpn livincr- fhp fhnrarir FlG - 578. — Ctw&ex americana. Abdomen 



waxy Dioom wnen mmg, me tnoracic except first segment . 7> ?> p> p i eur j t es; t, t, t, 



legs are Well-developed and five- tergites; S, S, S, sternites; cr, cercus; sp, spiracle. 



jointed; and the abdomen bears eight ter no grass ' 



pairs of prolegs. The larvae live free upon foliage upon which they feed. 

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

 common sawflies. The female is about § of an inch in length and has a black 

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

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



