i66 



THE STUDY OF INSECTS 



Fig. 293. 



diabroticas. Diabrotica longicomis is a green species, which feeds on the 

 pollen and silk of corn and on the pollen of other plants. Its larva is 

 Known as the corn rootworm; it is very destructive to corn in the 

 Mississippi Valley. Its injuries are greatest where corn is grown on the 

 same land year after year; hence a rotation of crops should be practised 

 where this pest is troublesome. 



The jlcabeetles. — There is a group of leaf-beetles, of which we have 

 many species, in which the hind legs are fitted for leaping, the thighs 



being very large. These are commonly 

 called the fleabeetles. 



The striped fleabeetle, Phyllotreta vit- 

 tdta, is exceedingly common on cabbage, 

 turnip, radish, mustard, and 

 allied plants. It is a small, 

 black, shining beetle, with a 

 broad, wavy, pale, dull yel- 

 low stripe upon each wing- 

 cover (Fig. 293) ; it measures 

 about -jV of an inch in length. 

 These beetles eat numerous 

 little pits in the thicker leaves that they 

 infest, and minute perforations in the thin- 

 ner-leaved plants. The larva is a slender, 

 white worm, about | of an inch in length ; 

 it feeds on the roots of the plants infested by the 

 adult. 



The cucumber fleabeetle, Epitrix ciiciimeris, is a 

 common pest of melon and cucumber vines ; it also 

 attacks the leaves of potatoes, raspberry, turnip, 

 cabbage, and other plants. This is a minute black 

 species, measuring less than -^ of an inch in length. 

 The body is finely punctured and clothed with a 

 whitish pubescence ; there is a deep transverse furrow across 

 the hind part of the prothorax; the antennae are dull yellow, 

 and the legs are of the same hue, except the posterior femora, 

 which are brown. The adult beetles 

 feed on the leaves of plants in the 

 same manner as the preceding spe- 

 cies ; and the larvae on the roots of the t 

 infested plants. 



The grape fleabeetle, Haltica 

 chalybea. — This is a larger species 

 than the two preceding, measuring 

 about \ of an inch in length, and is of 

 a dark, steel-blue color. It is a great pest in vine- 

 yards, eating into the buds of grape in early spring, 

 and later gnawing holes in the leaves (Fig. 294). In 

 May and June the brown, sluggish larvae may also be found feeding upon the 

 surface of the leaves. The full-grown larva is chestnut brown marked with 

 black spots (Fig. 295) . It drops to the ground and makes a cell in the earth in 

 which it transforms. The most important injury caused by this pest is the de- 

 struction of buds in early spring, which causes a great loss of foliage and fruit. 



Fig. 



