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Cotton Insects

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COTTON INSECTS. The cotton worm and boll-worm are the chief enemies of the cotton plant in the United States; in other countries different insects prey upon it. Vari ous caterpillars and other insects attack this plant wherever it is grown. In Egypt a noctuid larva, in Greece various kinds of cut-worms, in India a small tineid boll-worm (Depressaria), while in Australia a red-bug, allied to. the cot ton-stainer (Dysdercus suturellus) affects it. This insect, by sucking the buds, causes the bolls to blast or become diminutive, and also stains the cotton fibre by its excrement.

The cotton worm is by far the most serious pest. It is the larva of a noctuid buff moth (Aletia xylina), which often feeds in vast num bers on the leaves of the cotton-plant. Ala bama argillacea is a semi-looper caterpillar, has a loping gait; is slightly hairy, green, dotted with black along a subdorsal yellowish line, with black dots beneath. The insect, as shown by Riley, '(never hibernates in either of the first three states of egg, larva, or chrysalis, and it survives the winter in the moth or imago state only in the southern portion of the cotton belt.* The moth,' he adds, "hibernates principally under the shelter of rank wire-grass in the more heavily timbered portions of the South, and begins laying its eggs (400 to 500 in number) on the ratoon cotton when this is only an inch or two high." The localities where it hiber nates, and where, consequently, the earliest worms appear, seem to be more common in the western part of the cotton belt (Texas) than in the Atlantic cotton States. It is inferred that from this region the moths emigrate east and north, laying their eggs later than the original Texan brood, as in Alabama and Georgia. The recently hatched worms of different sizes were found late in March on ratoon cotton in south ern Georgia and Florida, and in late seasons from the middle of April to the middle of May, though they do not• attract the attention of planters until the middle or last of June. In midsummer the period from hatching to the time when the moth lays her eggs is less than three weeks, but in spring and late autumn twice that time may be required. There are thus in

the northern cotton States at least three "crops' or broods of caterpillars in a season, while in Texas there are at least seven annual genera tions. The first generation is only local, but in Texas, says Riley, "the third generation of worms may become, under favorable conditions, not only widespread, but disastrous, and the moths produced from them so numerous that they acquire the migrating habit. This genera tion appears in southern Texas during the latter part of June, and in southern Alabama and Georgia somewhat later,' and this is the first brood which attracts general attention. When the worms are very abundant and the cotton well "ragged,' the moths, driven by need of food and with favoring winds, migrate to dis tant points, and thus spread late in summer, having been seen as far north as Massachusetts and the Great Lakes.

Another insect, destroying great numbers of cotton buds, is the boll-worm, the caterpillar of another noctuid moth (Heliothis drmigera), well known for its injuries to tomato and tobacco plants and to corn in the ear. The adult is a tawny, yellowish moth, about an inch and three-quarters across the wings, which may be seen toward evening, in summer and autumn, hovering over the cotton blooms, and depositing a single egg in each flower; the egg is hatched in three or four days, and the worm eats its way into the centre of the boll, causing its pre mature fall; the insect instinctively leaves the boll when it is about to fall and enters another, and finally attacks the nearly matured bolls, rendering the cotton rotten and useless. The caterpillars have 16 feet, and creep with a grad ual motion, unlike the true cotton worm; they vary much in color, some being green, others brown, but all more or less spotted with black, and having a few short hairs. A single moth will lay 500 eggs, and as three broods• are pro-. duced in a year, a whole field will be very soon infested with them.

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