THE PLACE OF SPIDERS IN NATURE 17 



They live under stones, in moss, leaves, or debris on the ground, 

 under the bark of trees, in the nests of bees, ants, and termites, and 

 often in the dwellings of man. Many are found only in caves. One 

 of the better-known species, the large, cosmopolitan Chelifer can- 

 croides, lives in houses and shelters of man all over the world. 



The food of pseudoscorpions is believed to consist of mites, 

 psocids, springtails, and other tiny insects, which are grasped with 

 strong claws and perhaps anesthetized by venom from tiny glands 

 in the chelicerae. Along with the spiders and some of the mites, 

 the pseudoscorpions share the ability to produce a kind of silk. It 

 comes from glands that are probably homologous with those that 

 in spiders produce the venom to subdue prey. During periods when 

 they are relatively helpless, such as when the female is distended 

 with eggs, or when molting, they spin silk copiously and enclose 

 themselves in wonderfully constructed nests or retreats. As is true 

 of most arachnids, the pseudoscorpions have very poor vision, and 

 frequently eyes are lacking altogether. The numerous sensory hairs 

 on the pedipalpi and on other parts of the body take the place 

 of eyes. 



The pseudoscorpions frequently attach themselves to the bodies 

 of such insects as flies and bettles, and are thus transported quickly 

 from one locality to another. 



Harvestmen. Familiar to most people because of the great length 

 and thinness of their legs, the harvestmen, or daddy-long-legs, 

 scarcely need introduction. Though often confused with spiders, 

 to which they have a certain resemblance, they can always be dis- 

 tinguished from their spinning relatives by the body, which has the 

 cephalothorax and abdomen broadly joined to form a single unit. 

 In this respect they are similar to the mites but differ from them in 

 having the abdominal portion with well-marked segments. 



Most of the harvestmen (Plate IX) found in the temperate zone 

 are active creatures that run rapidly on stilt-like legs, which they 

 shed readily when in danger of being caught. They often congre- 

 gate in considerable numbers on vegetation or on the trunks of 

 trees, and are especially noticeable during the harvesting season, a 

 fact that has inspired the common name. The harvestmen seem to 

 feed largely on dead insects, but are also known to kill small ones 

 for food, and to suck juices from various soft fruits and vegetables. 



The long-legged harvestmen are partially replaced in the warmer 

 parts of the United States and in the tropics by shorter-legged spe~ 



