206 



INSECTS AFFECTING FIELD CROPS 



immune; it is, however, eaten if found in the line of march. Figure 

 220 illustrates a closely allied form. 



Control. Various parasitic two-winged and four-winged flies 

 attack it. Barriers may be constructed to check its march. These 

 are described in connection with another form of army worm, 

 and also in connection with remedies advised for chinch bugs. 



Deep fall plowing and thorough harrowing will help to destroy 

 hibernating larvse. Where safe and feasible, burn the grass along 

 fence rows and hedges or waste places where larvse normally live. 

 A strip four feet wide across their line of march, dusted or sprayed 

 with Paris green or other arsenical poison, may be effective. 

 When gathered in furrows plowed to check their march, they may 



FIG. 221. Wire worm and "click beetle 



be destroyed by spraying with pure kerosene or crude petroleum, 

 or straw may be placed over them and burned. Whatever remedy 

 or remedies are chosen by the farmer, prompt action is necessary 

 in order to save certain crops. 



Wire Worms. The adults are known as click beetles (Fig. 

 221) or snapping beetles, from the fact that if they are placed upon 

 their backs they recover their normal position by a quick contrac- 

 tion of muscles, causing the forceful moving of the thorax upon 

 the abdomen, which is accompanied by a clicking sound. They 

 are from one-half to three-fourths of an inch long. They are brown, 

 brownish gray, or black in color. Their larvse, called "wire 

 worms," are slender, cylindrical, hard, shining brown or yellow 

 grubs, about three-fourths of an inch long (Fig. 222). 



