POTATO BUG, or COLORADO POTATO BEETLE, a name now generally applied to a coleopterons insect, the don/pliora decem-lineata of Say. It is indigenous to the canons and table-lands of the Rocky mountains, where it feeds upon various wild species of solanum (S. rostratum and cornuturn). As the cultivated potato began to be intro duced westward into or towards those rerions, the beetle commenced feeding upon it, and the abundance of food thus furnished has caused a great multiplication of the pest, and its rapid extension eastward. It commenced its ravages in 1859, and for the past five years, that is, since 1876, it has become naturalized in the potato-growing sections throughout the United States and Canada. Its natural history was first made known in 1863 by prof. C. V. Riley, the Missouri state entomologist. In 1865 it crossed the Mis sissippi river into Illinois and Wisconsin. In 1867 it invaded Indiana and Michigan, and in 1868 it visited Ohio. In 1875 it reached the seaboard, marching faster in the more northern portions because thriving best in the cooler climates, and where the soil is less affected by the droughts of summer. It does not pass through the country, but extends into it, leaving permanent colonies behind. After the first few years, however, these do not flourish as well as the immigrants and their first descendants, because of the increase of parasites and other enemies which live upon them. The beetle in its perfect state is about one-third of an inch long, of a hemispherical shape, and of a yellow color, with ten black stripes on its elytra, or wing covers, five on each elytron. It passes the win ter in the ground beneath the frost at various depths (hibernating), sometimes going 2 or 8 ft. beneath the surface, depending upon the nature of the soil, the average depth being, in the middle states, perhaps from 0 to 12 inches. Soon after the frost is out of the ground and vegetation starts in the spring, and before the potatoes are up, the bug issues from its sleeping place. Whatever else it may feed upon, it does not wait for the potatoes to come out of the ground, but will find the young shoots beneath the surface and commence its depredations. As soon as the leaves are exposed to the air the females commence to lay their eggs, which are deposited in clusters of from 10 to 40 or more, on the under side of the leaf. They are of an orange color, and oval in shape. They hatch within a week, producing dark, dull-red larva;, which gradually assume a lighter color and acquire two rows of blac:K spots on each side. The legs, the head, and the poste rior half of the first joint H re also black. The larvae feed voraciously upon the potato leaves and become full grown in about 20 days, when they crawl into the earth to pass through the pupa and into the beetle state, nil of which is accomplished in about five weeks from the time the eggs are laid, or a little over four from the time of hatching. Mr. Riley- says that there are three broods produced in one season in the latitude of St. Louis.. These broods are, however, not all developed at regular intervals, but owing to the fact that the ovaries continue to develop eggs for a considerable time, each female lays several batches at intervals. Mr. Riley estimates the average number laid by one feinalb to be from 500 to 700. Whole potato crops, sometimes covering scores of acres in a body, have been swept away in a few days by the ravages of the myriads of dis gusting lame of these beetles. In portions of the country where potatoes are grown near the seacoast, as on the southern shore of Lone Island, the insects have either flown or been driven into the waves by the wind in such numbers as to form considerable ridges on the beach when washed ashore; not dead, however, but able to crawl and fly away. They will feed upon other plants of the solanacem, but without the cultivated
potato they could not multiply as they do. In emergencies they sometimes feed upon other plants, such as pig-weed, maple-leaved goose foot, and some other weeds. For tunately they have active enemies, viz., insectivorous birds (q.v,), parasitic and preda tory insects, and man. The only true parasite of the potato bug is a dipterous insect, a tachinm fly (lydella doryplu»•a), about the size of the common house fly. This insect Jays its eggs on the body of the larva of the beetle, and when the eggs hatch their Larva enter that of the beetle, and descend with it into the ground when it goes there to be transformed, this process being arrested, however, by its translation to the bodies of the tachinm larvae. Many of its enemies are predatory insects of its own order, coleoptera, as the fieryground.beetle, and others of the earabithe, who seize and devour it; several species of lady-bird (q.v.) feed upon its eggs. Other insects of the dipterous and hem iptcrous orders also pounce upon the beetle and suck its juices, or feed upon it. But as tae bug is a greater enemy to man than to anything else, so man is the bug's greatest enemy, and with the use of arsenite of copper, or Scheele's green, commonly called Paris green, he destroys myriads of the pests, and, when persistent and industrious, succeeds in saving his potatoes. There are two modes of using this effective poison; one is to mingle a large tablespoonful of it with about three gallons of water, and sprinkle the attacked plants with a fine sprinkler, once or even twice a day. This is quite rapidly done by active men, each man going between two.rows and sprinkling both. The other and most favorite method, the result of recent vials, is to mingle the Paris green with plaster of Paris in the proportion of one part to 25 or even 50 parts of the latter. and dust the leaves of the plant. This does not wash off as soon as tha simple watery mixture, as the plaster is not very soluble, and in uniting with a certain portion of atmospheric moisture, forms a thin film or crust, which does no injury, but, remaining as it usually does, if rains are not heavy, a few days, is a protection against the bugs. The applica tion is made with a spoon or some instrument answering the same purpose, as it is dan gerous to use the hands. No bad effects upon the persons of the operators have been known to follow the use of this poison by either of these methods, except with the grossest carelessness, and no injury is done to the plant with anything short of an exces sive and unnecessary quantity; neither is the soil made injurious to other vegetation, as far as the observations of good authorities go.—There is what is called a bogus Colorado potato beetle, the doryphora junta, which much resembles the genuine pest, and has been mistaken for it, but the larva have only one row of lateral black spots, and the stripes on the clytra are differently arranged. In the bogus bug the second and third stripes, counting from the lower edge, are joined at the ends, whilst in the potato bug the third and fourth stripes are the ones whose ends are united. The bogus bug, or dmvphora juneta, does not feed upon the potato, or has not thus far, but upon the will horse-nettle (solanum earolinense), and upon close examination the two species are found to have several marked differences. See COLORADO BEETLE, ante.