Helena Heath.
INSECT WAYS AND MEANS.
XI.—CATERPILLARS AND THEIR ENEMIES.
The caterpillar of the North American Great Peacock moth (fig. [4]) is armed with numerous tufts of prickles ending in minute black points which pierce the hand if touched, and cause severe pain. These spines, as shown in the illustration (fig. [2], a b, on page [357]) are hollow, and filled with liquid poison. 'a' is the portion which breaks off; 'b' the hollow base which contains the poison.
In some few caterpillars the poison spines take the form of balls armed with short prickles and one large spike; hence they are known as caltrop spines (fig. [2], c), from their likeness to the cruel weapons, known as caltrops, which used to be scattered over the ground in time of war to repel the attacks of cavalry; the spikes forced their way into the horses' feet when trampled on, and so disabled them.
The spines of the caterpillar of our Oak Eggar moth are very brittle, and in handling these insects, great care must be taken, as cases are known of blindness having been caused by the spines being carried into the eyes by the fingers.
Let us now turn to the liquid squirts with which some caterpillars are provided. Our Spurge-hawk caterpillar, for example, when threatened, squirts from the mouth a spray of poison. In our illustration (fig. [5]) it is shown repelling the attack of the dreaded ichneumon fly by means of this spray. The quaint Puss moth, which many Chatterbox readers must have seen, can squirt out an irritant fluid, generally supposed to be formic acid, from the mouth, when alarmed, and this, if it enters the eye, causes acute pain.