110 



NATURAL HISTORY OF ARTHROPODS. 



draws out a band of fine threads, which she reaches out toward the insect with one of 

 her hind feet, so that it may strike the threads as it kicks, and become entangled with 

 them. As soon as the insect is tied tightly enough to be handled the spider holds and 

 turns it over and over with her third pair of feet, while with the fourth pair she draws 

 out, hand over hand, the band of fine threads which adhere to the insect as it turns, 

 and soon cover it entirely. 



It is a common habit with spiders to draw out a thread behind as they walk along, 

 and in this way they make the great quantities of threads that sometimes cover a field 

 of grass or the sides of a house. 



In confinement spiders begin at once to spin, and never seem comfortable till they 

 can go all over their box without stepping off their web. 



The uses to which the silk is put are very various, the principal being in the forma- 

 tion of nest, webs, and egg-cocoons. Among the simplest nests are the very interesting 

 tubes of the Trap-door spiders, principally belonging to the Mygalidae. Cteniza cali- 

 fornica, common in New Mexico, Arizona, and California, digs its hole in a fine soil, 

 which, when dry, is nearly as hard as a brick. The holes are sometimes nearly an inch 



FIG. 156. Nests of trap-door spiders. A. Nest of Atypus. B. Nest with thick door. C. Nest with thin door. 

 D. Branched iiest. E. Nest with two doors. F. Branched nest with two doors. G. Nest with two branches. 



in diameter, and vary in depth from two or three inches to a foot. The mouth is a 

 little enlarged, and closed by a thick cover that fits tightly into it, like a cork into a 

 bottle. The cover is made of dirt fastened together with threads, and is lined, like 

 the tube, with silk, and fastened by a thick hinge of silk at one side. When the cover 

 is closed, it looks exactly like the ground around it. The spider holds on the inside 

 of the door with the mandibles and the first two pairs of feet ; while the third and 

 fourth pairs are pressed out against the walls of the tube, and hold the spider so firmly 

 that it is impossible to raise the cover without tearing it. 



Among the trap-door spiders of Southern Europe are species which make different 

 kinds of nests. The cover, instead of being thick, and wedged into the top of the 

 tube like a stopper, is thin, resting on the top of the hole, and is covered with leaves, 

 moss, or whatever happens to be lying about ; so that it is not easily seen. Two or 

 three inches down the tube is another door, hano-ino- to one side of the tube when not 



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in use ; but, when one tries to dig the spider out from above, she pushes up the lower 

 door, so that it looks as if it were the bottom of an empty tube. 



Another species digs a branch obliquely upward from the middle of the tube, closed 

 at the junction by a hanging-door, which, when pushed upward, can also be used to 



