TRAP-DOOR SPIDER. Any one of the large hairy tropical spiders belonging to the fam ily Theraphosidm, which make long tubes in the earth, lining them with silk and furnishing them at the entrance with a bevel-edged, hinged, ac curately fitting trap-door made of alternate lay ers of earth and silk. The upper surface is cov ered with earth or gravel so as to completely dis guise the entrance. The spicier hides in the nest when not seeking its prey, and with some species a branch to the tunnel is built with a separate door.
The digging of the burrow, which is always on high sloping ground, is a very laborious task. The earth is loosened with the mandibles, and is carried away piece by piece supported by the mandibles and maxilke. One observed by Itlogg ridge took an hour to dig a hollow as large as half a walnut. A species common in the South western United States (Ctenitza Californica) digs holes nearly an inch in diameter, and some times a foot in length. When the spider is on guard, holding the door down from inside by means of its mandibles and feet, it is impossible to raise the trap-door without tearing it. Ex perimenters at San Diego, California, removed the trap-doors of sixty nests, unhinging them at night. Without exception the spider had by morning completed a new door. Continued re
moval, however, resulted in a falling off in the quality of the successive doors owing to the fail are of the spider's supply of silk. The fifth door made, by a single spider, was composed almost en tirely of mud with hardly enough web to coat and binge it. When the trap-doors were fast ened down a side branch with a new door was always made over night with an opening near the original mouth.
The nests are generally built in pairs, but it is not known whether they are occupied by different sexes. The young hatch in the mother's burrow, and live there for a few weeks; then they leave the nest and begin small tubes of their own. The food of these spiders consists largely of ants and other crawling wingless insects. They have been known to eat earthworms and large caterpillars. The trap-door spiders of Southern Europe make thin covers which rest loosely on the top of the hole, but they are covered with leaves or some thing of the sort in order to disguise them.
Consult: Moggridge, Harresting Ants and Trap-Door Spiders (London, 1873) ; Emmerton, The Structure and Habits of Spiders (Salem, 1873) ; McCook, American Spiders and Their Spinning Work, vol. iii. (Philadelphia, 1893).