170 INSECTS AFFECTING VEGETATION 



an inch to more than an inch in length. All have hard, polished 

 skins amounting almost to shells, and six short legs just behind 

 the flattened heads, besides a sucker-like false-foot on the last seg- 

 ment. Wire-worms usually feed on the roots of grains, corn and 

 other grasses, though they will not refuse potatoes when occasion 

 offers. There are many species to be found, and while one may pre- 

 fer corn, another wheat, and so on, they may all be considered as 

 injurious, except those found in rotting wood, and treated together. 

 The adults are the common snapping-beetles or click-beetles, the 

 little fellows that jump up into the air -with a click, when placed on 

 their backs. These beetles lay the eggs from which the wire-w r orms 

 hatch, and the wire-worms in turn become click-beetles after passing 

 through a chrysalis stage in their little earthen cells in the soil. It 

 is probable that two years are required by the larvae to attain matu- 

 rity. The winter is passed in little cells in the soil in some cases, 

 while in others the adult beetles emerge in the fall and hibernate. 



Wire-worms are primarily insects of grassland and the fact that 

 they require two or three years to develop helps to explain why it 

 is that they are often worse the second year after grass than they 

 are the first, most of them being full-grown at that time. 



In corn, the most noticeable injury is to the seed after planting, 

 though the larvae also feed on the roots after the corn is up. A 

 long series of experiments by Professors Comstock and Slingerland 

 of Cornell University, failed to show any practicable method of treat- 

 ing the seed so as to prevent injury by wire-worms. They did 

 show, however, that late fall plowing killed many of the pupae and 

 adults by breaking open the earthen cells in which they were. They 

 failed also to kill the wire-worms by any of the commercial fertiliz- 

 ers or insecticides, unless these were used in excessive quantities. 



Prof. S. A. Forbes, State Entomologist of Illinois, proposes a 

 rotation of crops in which the clover shall always follow grass, and 

 corn shall always follow clover. Plow the grass in early fall, and 

 sow clover, either with oats, wheat or rye. Allow the clover to stand 

 two years and follow with corn. On general principles it is well to 

 use wood-ashes where obtainable, because of their tonic effect on the 

 plants. It is understood, of course, that these practices are recom- 

 mended for aggravated cases of wire-worm infestation and not for 

 regular use in the absence of the pest in dangerous numbers. 



Corn and Timothy Bill-Bug. The timothy and corn bill-bug 

 is a small beetle that habitually works in timothy, where its work 

 is naturally more or less obscure. When, however, corn follows in- 

 fested timothy, or when corn is planted near infested timothy, it is 

 likely to be attacked. 



The beetles are less than one-fourth of an inch long, and are 

 black. They belong to the group of snout-beetles. In young corn 

 they tunnel directly into the plants just above the crowns, causing 

 the plants to wilt and usually to die. Fortunately the beetle pro- 

 duces but one generation each year, and the injury, so far as corn is 

 concerned, is done by the adult beetles alone. 



