All insects have a continual struggle for life. They constitute the food of many birds, and very few of the young escape these watchful creatures and attain mature life.

To enable the insects to escape, nature has given many a strange protective garb, which is called mimicry or a protective resemblance. Sometimes it is color, an insect mimicking a leaf in color; or again, the insect imitates a twig or leaf in shape, and so escapes attention. We find examples of this in many families, but particularly among the insects now under consideration. The mantis (Fig. 192) belongs to a group in which the insects resemble twigs in shape and color, and nothing could be more striking than these strange, slow-moving creatures. They have an uncanny, weird appearance, and look as though they might have been originally of wood. I have seen them in the tropics passing slowly along a limb, lifting one leg at a time, moving it with all the halting deliberation of an automaton; but when the mantis perceived me, it stopped just as it was, the foot that was in the air remaining as though it had been frozen in the act. Some are a vivid green, and in them the resemblance to twigs is very striking. I once encouraged a number to live in my preserves, where I watched and studied and often fed them. They would take a fly from my hand by a very rapid movement of the cruel, fore hands or claws, which were toothed. When food was scarce the insects would devour one another in the most deliberate fashion, then assume the quaint, supplicating position with claws up, from which the insect is called the praying mantis. My specimens deposited their eggs in a curious case about an inch long, resembling a trilobite, which they attached to the fence and colored the exact hue of the latter. The fence was not painted, and varied in color, yet the nests always agreed more or less exactly with the shade or tint of the plank or base to which it was attached.

In South America is found a huge mantis so powerful that it captures birds by grasping them in its terrible claws. The insect is described by Burmeister as crouching on the limb, imitating it so closely that the bird approaches it without fear. In Java a beautiful pink mantis is so perfect in its mimicry of a pink orchid that insects alight upon it and are caught. A Philippine Island mantis is remarkable for its resemblance to a dried and withered leaf.

The chief characteristic of this insect is its cool, deliberate ferocity—devouring its mate with indifference, lunching calmly upon its young, while they are dining among themselves. When fighting they have the characteristics of the bulldog, with many times its endurance. A mantis will continue a combat even when part of its body is cut away. I have seen one deprived of all its legs cling to a limb with one claw and continue to reach for its foe with the other.

Closely allied to the mantis, and even more remarkable as mimics, are the walking sticks (Phasma) (Fig. 193). I have kept them alive, and often have been unable to see them when I knew they were directly beneath my eyes, so remarkable is the mimicry. They have no biting claws, merely long antennÆ, a long, sticklike body, and straight-jointed, sticklike legs. Some are green. The most remarkable are those which seem to imitate dead wood. I have seen a walking stick that was a perfect imitation of a moss or lichen-covered twig, the body and legs of the insect being covered with peculiar growths. The largest walking stick I have seen was twelve inches in length, and one of the most perfect imitations of a green twig that could be imagined. This was from the Malay country, where they grow to a length of fourteen inches. They stretch out upon long tendrils, extending the limbs or holding them up, the poseurs of the insect world.

The walking leaves (Phyllium) (Fig. 194) are clever mimics, resembling leaves. Even the veins and midrib of the leaf are imitated, and the insect, when crouching on a limb, is a virtual leaf, so far as appearance goes, the disguise being absolutely perfect. Some resemble green leaves; others dried and withered specimens. Even the legs of these insects are supplied with a singular growth. Most of these strange mimics are found clinging to trees; but one common in Brazil spends most of the time during the day under water in streams, where it clings to the pebbles. In Nicaragua there are several species that resemble leaves in all stages of decay. The movements of some of these insects resemble those of leaves. I saw one in the Sierra Madre range come down from a tall sycamore, and supposed it a leaf, as it dropped slowly, zigzagging down. I should not have discovered the mistake had not my dog recognized it.