ONION, INSECTS INFESTING. Within the last ten years the onion crop of the United States has been seriously infested with insects, especially with the maggot, the larva of a European fly, and also a native species, which seem to have multiplied rapidly from some unknown cause. A minute Thrip, Limothrips tritica has also made its appearance. The cut, Fig. 1, shows the insect in its several stages, magnified, the hair lines showing the natural size. The figures a, b, show larvae; a, male; b, female, and the figure at the right shows the antenna very highly magnified, as will be readily understood, when we recollect that the adult is less than an eighth of an inch in diameter; c, per fect insect. Of the onion fly, there are two species, the Native Onion Fly and maggot, (Ortalie flexa) shown at Fig. 2, enlarged, the hair line natural size. Fig. 8 shows the European Onion Worm, (Anthomyta ceparum), imported into the United States over forty years ago; a, natural size ; b, maggot, and c, the fly magnified, the hair lines giving the natural size. The report on the Rocky Mountain Locust, and other injurious insects, for 1877, describes both species. The fol lowing is partly taken from the reports of Dr. Fitch, New York. Speaking of the imported fly, we find that in June, as soon as the young seed ling-onions are only an inch or two in height, these insects commence their depredations and continue them through the whole season, getting their growth and coming out in their perfect state one after another, whereby some of the flies are liable to be always present in the garden, in readiness to deposit their eggs; and maggots of widely different sizes are commonly met with in the same onion. The eggs or fly-blows are loosely placed upon the onion slightly above the surface of the ground, some being dropped along the thin edge of the sheath or white membraneous collar, which is formed by the base of the lower leaf clasping around the stalk, and others are crowded into the crevices between the bases of the leaves, slightly above where they issue from this sheath. From two to six or more eggs are usually placed on partic ular plants here and there through the bed.
They are perceptible to the eye, being white and smooth, four-hundredths of an inch (0.04) long, and a fourth as thick and of an oval form. hen the minute maggot hatches from the egg, it works its way downward inside of the sheath, its track being marked by a slender till it reaches the root, on which it feeds it is wholly consumed, only the thin outer skin remaining. After eating the bulb of one plant they attack the next, until sometimes a third or a half of the bed is destroyed. The
maggot attains its growth, in summer, in about a fortnight, and changes to a pupa either in the cavity in the onion, or in the wet, slimy earth which is in contact with the onion. It here ceases to move, it becomes contracted and shorter in length, its skin hardens and changes to a tarnished ,yellow and finally to a chestnut color with a stain of black at each end This is the pupa-case, and the true pupa is inside. In this condition.it lies about two weeks before the fly escapes. As a preventive measure trial the seed should be sown two inches deeper than usual, so that the fly can not so readily get to it to lay its eggs. Sow also on ground on which straw has been previously burned Rota tion of crops is also a most important prevent ive measure. When the roots are infested pour boiling water along the drills near the roots, or even on the plants, going over the bed four times during one season. The diseased onions should be pulled up and burned. Fitch recommends cultivating the onions in hills, scattered amoi g the other vegetables in the garden. With only three or four seedlings in a hill it is evident that the young worms could nowhere find a suffi cient amount of food to nourish them to maturity. Having consumed all the young plants in one hill, they will be unable to work their way through the ground to come at another hill except it be by the merest chance, and will thus perish. The Black Onion Fly was first found to be destructive to onions in Illinois by Dr. Henry Shimer, who writes as follows regarding it. In the latter part of June I first observed the larva or maggot among the onions here; the top dead, tuber rotten, and the maggots in the decayed sub stance. From them 1 bred the fly. They passed about two weeks in the pupa state. At that time I first observed the flies in the garden, and now few are to be found. Their favorite roosting place is in a row of asparagus running along the onion-ground, where they are easily captured and destroyed, from daylight to sunrise, while it is cool and wet. During the day they are scattered over the ground and on the leaves and stalks of the onions, and not easily captured. Their wings point obliquely backward, outward, and upward, with an irregular jerking, fan-like movement; flight not very rapid or prolonged. All that 1 observed originated in one part of the bed, where they were doubtless deposited by one parent fly. Two broods appear in a season.