When we consider the reputedly poisonous larvæ of moths and butterflies, one of the first things to impress us is that we cannot judge by mere appearance. Various species of Sphingid, or hawk-moth larvæ, bear at the end of the body a chitinous horn, which is often referred to as a "sting" and regarded as capable of inflicting dangerous wounds. It would seem unnecessary to refer to this absurd belief if it were not that each summer the newspapers contain supposed accounts of injury from the "tomato worm" ([fig. 29]) and others of this group. The grotesque, spiny larva ([fig. 30]) of one of our largest moths, Citheronia regalis is much feared though perfectly harmless, and similar instances could be multiplied.
But if the larvæ are often misjudged on account of their ferocious appearance, the reverse may be true. A group of most innocent looking and attractive caterpillars is that of the flannel-moth larvæ, of which Lagoa crispata may be taken as an example. Its larva ([fig. 31]) has a very short and thick body, which is fleshy and completely covered and hidden by long silken hairs of a tawny or brown color, giving a convex form to the upper side. Interspersed among these long hairs are numerous short spines connected with underlying hypodermal poison glands. These hairs are capable of producing a marked nettling effect when they come in contact with the skin. This species is found in our Atlantic and Southern States. Satisfactory studies of its poisonous hairs and their glands have not yet been made.
Sibine stimulea (Empretia stimulea), or the saddle-back caterpillar ([fig. 32]), is another which possesses nettling hairs. This species belongs to the group of Eucleidæ, or slug caterpillars. It can be readily recognized by its flattened form, lateral, bristling spines and by the large green patch on the back resembling a saddle-cloth, while the saddle is represented by an oval, purplish-brown spot. The small spines are venomous and affect some persons very painfully. The larva feeds on the leaves of a large variety of forest trees and also on cherry, plum, and even corn leaves. It is to be found throughout the Eastern and Southern United States.