In examining the various families of insects it is interesting to note that many produce certain results or accomplish certain ends in totally different ways. The highly organized spider by drawing silk from the spinning machines at the tip of its abdomen builds a web so strong that it sometimes captures birds. I recently found a living humming bird hard and fast in a web at the corner of my house, and released it just in time to save it from the spider. In the very lowest groups of insects we find the Peripatus (Fig. 163), which spins a weblike structure from glands in its mouth, ejecting the secretion at the insect it wishes to catch. This appears to crystallize in the air and hold the victim despite its struggles. The Peripatus, found in Africa and Central America, resembles a large caterpillar, having a long, soft, cylindrical body with many pairs of feet, sometimes sixty-six; the latter are soft and armed with claws. It is remarkable for the possession of many legs, but is outdone in this respect by the millipeds, as some (Fig. 164) have as many as two hundred. These insects, when placed upon their backs, present an extraordinary appearance, clawing the air; yet they are among the slowest of walkers. They live in the ground, are harmless, feed on vegetable matter, and deposit their eggs in the earth, which hatch out little creatures at first resembling crickets. [Illustration: FIG. 164.--A milliped.] [Illustration: FIG. 165.--A centiped.] The centipeds, on the other hand (Fig. 165), are animal feeders, and those found in the tropics are formidable creatures from six to ten inches in length, supplied with many claws and terrible fangs. They live a life of rapine and destruction, and the appearance of a large specimen almost a foot in length, dashing along with great rapidity by the aid of its fifteen or twenty pairs of feet, is sufficient to demoralize the stroller through the dark glades of the tropical forests. They have two pairs of foot jaws (Fig. 166) which grasp an enemy with wonderful tenacity. The second pair is perforated, and from it pours a poison dangerous to man in some tropical species and fatal to small animals. Several of these hideous creatures are luminous at times. Many centipeds have long antennæ. The eyes are very small, and in groups. The ordinary centiped of the North is harmless, despite the tales related of its ferocity. Among the very small, though destructive insects, are the mites, found in cheese and sugar; they are parasitic in cattle and various other animals. In California certain forms (Fig. 167) cling to the bushes. [Illustration: FIG. 166.--Under surface of head of centiped, showing poison fangs.] [Illustration: FIG. 167.--A mite.] [Illustration: FIG. 168.--The scorpion.]