The first brood stays under ground about a fortnight before it emerges in the perfect beetle state, and the second brood stays under ground all winter, and only emerges at the beginning of the following June. The perfect beetle (Fig. 11) is of a pale yellow color, with three black stripes on its back, and bears a strong resemblance to the cucumber-bug, (_Diabrotica vittata_, Fabr. Fig. 12.) From this last species, however, it may be distinguished by its somewhat larger size, and by the remarkable pinching-in of the thorax, so as to make quite a lady-like waist there, or what naturalists call a "constriction." The female, after coupling, lays her yellow eggs (Fig. 10,_d_) on the under surface of the leaves of the potato plant. The larvae hatching, when full grown descend into the ground, where they transform to pupae (Fig. 10, _c_) within a small oval chamber, from which in time the perfect beetle emerges. This insect in certain seasons is a great pest in the Eastern and Middle States, but has never yet occurred in the Mississippi Valley in such numbers as to be materially injurious. ~The Cucumber Flea Beetle~, (_Haltica cucumeris_, Harris.) This nimble minute beetle (Fig. 13) belongs to the flea-beetles, (_Haltica_ family,) the same sub-group of the leaf-beetles (_Phytophaga_) to which also appertains the notorious steel-blue flea-beetle (_Haltica chalybea_, Illiger) that is such a pest to the vineyardist. Like all the rest of the flea-beetles, it has its hind thighs greatly enlarged, which enables it to jump with much agility. It is not peculiar to the potato, but infests a great variety of plants, including the cucumber, from which it derives its name. It eats minute round holes in the leaf of the plant it infests, but does not always penetrate entirely through it. The larva feeds internally upon the substance of the leaf, and goes under ground to assume the pupa state. It passes through all its stages in about a month, and there are two or three broods of them in the course of the same season. This is emphatically the greatest insect pest that the potato-grower has to contend with in Pennsylvania. It abounds throughout most of the Northern, Middle, and Western States. Large fields of potatoes can any summer be seen in the Middle States much injured by this minute insect, every leaf apparently completely riddled with minute round holes, and the stalks and leaves appearing yellow and seared. Plaster frequently and bountifully applied is sure to prevent the attacks of this insect, or to disperse it after it has commenced operations.