GENERAL CROP PESTS 8l 



Wirewornis arc the offspring of snapping or click Ijcctlcs 

 or "snap-bugs," which arc rather liard, pubescent creatures of 

 elongate, oval form, and readily distinguishable from any other 

 insects by the habit from which their common name has been 

 derived, of vaulting into the air with a sudden click when they 

 happen to fall upon their backs. The common click-beetle 

 (Mclanotus communis Gyll.) is shown in figure 46. 



Of the various vegetable crops attacked potatoes, according to 

 record, are most injured, by having the surface of the tubers 

 gnawed into and eroded by the worms." Turnips suffer similar 

 injury, as do also to a less extent carrots, beets, cabbage, onions, 

 lettuce, and others. In attacking growing plants wirewornis 

 usually devour the smaller roots or tender tubers, according to 

 the plant affected, and in the case of attack on corn they fre- 

 quently kill the plant by boring cylindrical channels through 

 the under-ground portions of the stalk. 



The life histories and habits of wireworms vary according 

 to species and climate, but in many respects they resemble the 

 white grubs so closely that details may be omitted. 



The Cornell University experiment station carried on, through 

 Messrs. Comstock and Slingerland, a valuable series of experi- 

 ments against these pests extending over three years, with the 

 result that none of the alleged standard remedies produced 

 satisfactory effects. In short, the results were negative rather 

 than positive, and no single method has yet been devised by 

 which we can destroy these insects as we can most other pests. 

 This is due to natural causes — viz., to the hardness and con- 

 sequent hardiness of wireworms, two qualities which go hand 

 in hand as regards insects and which render these creatures 

 almost impervious to poisons that would destroy other insects, 

 and to the fact that they live during nearly their entire active 

 stage as wireworms usually rather deeply in the soil. They 

 require two or three years, like the white grubs, for full matur- 

 ity from egg to adult. 



