ARACHNIDA 107 



all directions attached to blades of grass for support. In the morning dew 

 these webs form a shimmering silken sheet. The spider runs about on 

 the upper surface of the " sheet " and catches any insects which light upon 

 it. The tube or hiding place opens below, so that the spider can escape if an 

 enemy appears upon the web. These are long-legged brown spiders, of 

 which the common grass spider is a familiar example. 



The "curled-thread weavers" are of two kinds, those which spin regular 

 webs and those which spin irregular webs. The curled thread is composed 

 of silk spun from a special organ, the cribel'lum, in front of the spinnerets. 

 It is combed into shape by means of stiff hairs called the calamis'trum on 

 the metatarsus of the hind legs, as the spider moves the hind legs rapidly 

 back and forth. 



Those spiders which spin irregular curled threads (Dictyn'idae) usually 

 make variously shaped webs on fences, under stones, in rotten logs, or upon 

 plants having clusters of small flowers like the golden-rod. 



There are but two genera of these spiders which spin regular webs 

 (Ulobor'idae) . The " triangle spider " is found all over the country in pine 

 woods. Its web is usually stretched between the twigs of a dead branch 

 of pine or spruce, and consists of four plain radiating lines and a series of 

 double cross-lines. The spider, which rests near one of the twigs from which 

 a strong line is drawn to one of the other twigs, pulls the web tight, so that 

 the cross-lines are separated as far as possible. When an insect lights 

 upon one cross-line the spider suddenly lets go, so that the whole web springs 

 forward and the insect becomes tangled up in the other cross-lines. 



The cobweb weavers (Theridi'idae) build their webs, which are ap- 

 parently only a shapeless maze of threads, in the corners of rooms as the 

 house spider or out in the fields between the leaves of bushes, or in the 

 fence corners, or among rocks. They are generally rather light colored, 

 small, and soft. They live in their webs, hanging by their feet, with the 

 back downward. The cocoons, several of which are made in one season, 

 are soft and round and hang in the web. 



The orb weavers (Epei'ridce) construct some of the most wonderful 

 homes built by any animal. First, there is an irregular outer framework of 

 supporting lines; then there is a number from twelve to seventy of dry 

 and inelastic lines radiating from the center. There is an inner spiral of 

 these inelastic threads which begins at the center and winds outward. 

 The rings of this spiral are about as far apart as the spider can reach. 

 Its use is merely for support. The spider then begins at the outermost 

 part of the web and spins an outer spiral of sticky elastic threads, winding 

 inward, the concentric circles being close together. As it becomes neces- 

 sary, in forming this outer spiral, the threads of the inner spiral are de- 

 stroyed. When an insect touches one of the outer sticky threads the thread 

 not only sticks to it, but it stretches so that the insect becomes tangled up 

 in the other circles, which is all the easier to do since the threads are so close 

 together. Many species strengthen the web by spinning a zigzag ribbon 

 across the center. The making of the entire web seems to be done alto- 

 gether by feeling and can be done in the dark as well as in the daylight. 



Most of the orb-weaving species have large, nearly spheric abdomens and 

 stout legs, sometimes " with humps and spines." These spiders are often 

 brightly colored, the colors of the abdomen being arranged in a triangular 

 or leaf-shaped pattern. Some species live near the center of the web, 

 hanging head downward, others hang back downward near one edge of the 

 nest. In some species the male is smaller than the female. 



