Of all the injurious agents most dreaded in the cotton-growing districts of the globe, none are so widely spread or so disastrous as "insect pests."
They attack different parts of the plant during its growth, and when the bolls are formed they commit great havoc among these by boring through and completely ruining the immature fibre. Then again, while the plant is young, they may attack the most tender portion of the plant, viz., the new and young leaves found at or near the top. This they soon clear and make their way as caterpillars down the plant, and they frequently clear it as though the leaves had been plucked off.
So completely do they do their work that it has been calculated in certain years the loss on this account alone cannot have been far short in America of 3-1/2 million pounds in one year.
Of the chief forms of insect pests, two specially stand out into prominence, both of which belong to the moth tribe of insects, viz., _Alethia argillacea_ or Cotton Caterpillar, and the _Heliothis armiger_ or Cotton Boll-Caterpillar.
The operations of the former are mostly confined to devastating the leaves and buds, while the latter confines its special attention to the bolls which, were they allowed to ripen, would burst with cotton.
The eggs of the former, too, are laid on the under side of the upper leaves and vast numbers are deposited. The moth flies by night, and the eggs laid are extremely difficult to discover--indeed it takes an expert to quickly find them.
Usually, about midsummer, the eggs are hatched in three or four days and then comes the period for spoliation.
All that is tender is assimilated, usually the under side of the young tender leaves found at the top of the plant.
During this stage of its existence the caterpillar moults five times and the larva period varies somewhat according to the weather from one to three weeks.
The chrysalis or pupa state covers from one week to four, and at last emerges as a beautiful olive gray moth with a purplish lustre.
In about four days the female commences to lay eggs very rapidly and will lay sometimes as many as six hundred during its life. No wonder, then, with several generations during a season and vast numbers of moths, that untold damages can be wrought by these particular insects in a single season.