INSECTS AFFECTING FIELD CROPS 491 



The wing-covers of the small bright-green beetle are marked 

 with twelve black spots. The beetle feeds on the foliage of 

 many garden and field plants, often doing considerable damage. 

 On account of this wide range of food plants it is not as easily 

 controlled as the preceding species, but crop rotation will still 

 be of some value. Sometimes it is profitable to plant the corn 

 so late that it will not come up until after the beetles have laid 

 their eggs on other plants. 



The Cora-root Web -worm (Cr ambus caliginosellus). This is 

 still another larva that attacks the roots and stalks of corn, 

 sometimes killing so many of the young plants that the field 

 must be reseeded. The yellowish or brownish little cater- 

 pillars, covered with a case made out of loose web and particles 

 of dirt, are usually found feeding in the corn plant below the 

 surface or close to the surface of the ground. The adults are 

 small, white and yellowish "grass-moths," so called because 

 they are so frequently seen flying from the grass when it is 

 disturbed. When the moths are at rest the wings are folded 

 close around the body. The larvae of the second generation 

 hibernate in their silken tubes, and are ready to begin feeding 

 as soon as the plants begin to grow. As the larvae live on the 

 roots of grasses, corn that is planted on new land will suffer 

 most. In well-cultivated fields where crop rotation and late 

 fall or early spring plowing is the practice the injury is usually 

 not so great. 



The Larger Corn-stalk Borer (Diatrce zeacolella). This in- 

 sect belongs to the same family of moths as the preceding species 

 but it is larger. The larvae live in the stalk of the corn, often 

 weakening it so that it is easily broken by the wind. In the 

 fall the caterpillars of the second generation bore deep into the 

 tap-root and there pass the winter, pupating early in the 

 spring. If the old stalks and butts are dragged together and 

 burned most of these over-wintering larvae will be killed. 

 Again, crop rotation is recommended as the best remedy. 



The Bill-bugs (Sphenophorus spp.). There are several 

 species of snout beetles, or weevils, that injure corn and other 

 field crops by attacking the stalk and roots. They are usually 

 injurious in both the larval and adult stages, and are hard to 



