The spiders are very solicitous of their young, placing every safeguard about them, and resenting any attack by a fierce rush. Several large spiders (Fig. 176) carry their young upon their backs. The little spiders are rubbed or scraped off when they become too great a burden. The spiders are natural hunters and trappers, and a volume could be written on their methods and adventures in running down prey. Once as I was crawling through the almost stifling brush of one of the Florida Keys I came to a little opening about five feet wide, across which was a large, conspicuous, and powerful web. In the center of this web clung a huge and most remarkable spider, colored a vivid yellow and black. I watched it for a few moments while resting, and then touched the web, whereupon the spider began to swing, by raising and depressing its body, increasing its speed rapidly, until I could with difficulty see it. A moment later it disappeared almost entirely before my eyes. For half a minute the spider kept up this motion, then it slowly came to a standstill, having demonstrated that it could easily disappear from any bird enemy without running away. I have seen the daddy longlegs perform the same feat in California. [Illustration: FIG. 176.--Spider with young upon its back.] The spiders which build webs, from plain geometrical traps to conelike affairs, are interesting; but the trapdoor spiders and those which dig burrows are among the wonderful artisans and engineers of the insect world. One of the most perfect doors, in hinge, fit, beauty of interior, finish, and quality of its outward defense is built by a spider (Fig. 177). In the illustration, the den and its trapdoor is shown, and in Figure 178 a sectional view of the same is seen; but the door is never found open, the spring or hinge being so devised as to remain closed. I have found many of these dens in southern California sometimes a foot or more in length. The spider is not the large one shown in the cut, which is a tarantula, but is very much smaller, though a large spider. The genera, Cteniza and Nemesia, are best known for their cunning and skill as builders. The California spider begins its den when very small, and I have found many the size of goose quills, with door complete, in the vicinity of a large den. [Illustration: FIG. 177.--Tarantulas (_Mygale_) and the opening of a trapdoor den of another spider (_Cteniza_).] [Illustration: FIG. 178.--Section of a den of trapdoor spider.]