INSECTS INFESTING T)[li SWKET POTATO 



241 



tion. The first application is to accomplish the destruction of 

 the heetles hefore they deposit their egi^s. and the second and 

 third are to kill beetles that may come from other plants. Rota- 

 tion of crops and the avoidance of plantins;- in the vicinity of 

 neglected ground that has grown up witli bindweed and wild 

 morning-glory are also advisal)le. 



The Common Sweet-potato Sawfly (Schicoccnis cbcnus Nort.). 

 — The larvae of two species of sawflies have been observed doing 

 injury to sweet potato. 

 They are comparatively 

 new as pests and of similar 

 habits and distribution from 

 New York to the Gulf and 

 northward to Nebraska. 



The present is like other 

 sawflies, four-winged, and 

 somewdiat smaller than a 

 house fly, the body is black, 

 and the wings infuscated 

 or dusky. The male has 

 forked antennae while the 

 female has shorter simple ones. Eggs are deposited in the leaf of 

 sweet potato. Attack has been observed in August and Sep- 

 tember in Mississippi, and a parasite (fig. 157) has been reared 

 from the larva. This parasite, and a tachina' fly, which also 

 preys on it, no doubt hold the insect in check and prevent 

 serious injury. 



The Larger Sweet-potato Sawfly {Schizoccnis privalns 

 Nort.).— The first record that we have of injury by the larvfe 

 of this sawfly was in July, 1890. when it damaged sweet potato 

 in Virginia. At that time plants that were attacked produced 

 no yield whatever. This sawfly is larger than the preceding, 

 the wing expanse being nearly 3/5 of an inch, and both sexes 

 have yellow abdomens. Other differences can be made out by 



Fig. \S7 .—Eubadizon schizoceri. Parasite of 

 sweet-potato sawfly. (After Insect Life) 



