342 



APPLIED ENTOMOLOGY 



Control. — Spraying with arsenate of lead, standard formula; Nicotine sulfate 

 40 per cent, 1 pt. in 100 gal. of water, with 3 or 4 lb. of soap; 1 oz. of white helle- 

 bore in 3 gal. of water; or dusting with freshly slaked lime, are effective treatments 

 for this insect, but it is not very often abundant enough to call for the use of 

 control measures. 



A similar saw-fly often attacks the rose, feeding on the leaves, its dark-colored 

 and slimy, though small, larvae being very noticeable when abundant. When 

 treatment is necessary the methods given for the pear slug are equally effective 

 with this insect. 



A few of the stem and wood borers in this superfamily are of considerable 

 importance, but most of them are seldom noticed. The Wheat-stem borer 

 {Cephus pTjgmceus L.) in the East and the Western grass-stem borer {Cephus 

 cindus Nort.) in the West often attack growing wheat. The adult (Fig. 357) 



Fig. 357.^ Western Grass-stem Borer (Cephus ductus Nort.): 3, base of wheat plant 

 showing larva in winter position; 5, adult Saw-fly; 6, full-grown larva. All natural size. 

 {Modified from Can. Dept. Agr. Ent. Branch, Bull. 11.) 



punctures the wheat stem in the spring and deposits an egg inside the stalk and 

 the larva which soon hatches, tunnels in the stem and as the grain ripens, 

 works its way downward, and by harvesting time most of them have reached 

 the roots. They then prepare for winter, cutting the stalk partly off, generally 

 less than an inch above the surface of the ground. Each now plugs the cavity 

 of the stem below this point for a short distance, leaving about half an inch of 

 space between the plug and the lower end of the cavity, in which it spins a cocoon. 

 The larva winters thus, pupates in March or April in New York at least, and 

 the adult appears in May. The life history of the western species is much the 

 same. 



Where grass-seed is not planted with the wheat, plowing the stubble under, 

 deeply, at any time between harvest and the following May, or burning the stub- 

 ble when this is possible, are two fairly efficient methods of control. Where it is 

 desired to lay down a field to grass and the insect is abundant it would be better 

 where practicable to use oats rather than wheat with the grass-seed. 



