SPIDERS AND MYRTAPODS 



257 



web a funnel-like tube runs downward and inward. In this tube the 

 spider spends most of the time, running out to catch insects which may be- 

 come entrapped. At the lower end of the tube is an opening through 

 which the spider may escape in time of necessity. The funnel-web 

 builders are strong-legged, active spiders. 



The orb-weaving spiders spin webs of geometrical exactness in bushes or 

 long grass. They are usually of almost circular form with a spirally wound 

 center thread supported on guy lines which are attached firmly to surround- 

 ing objects. These webs, which act both as homes and snares, are made 

 of two kinds of silk, a supporting thread, tough but rather inelastic, and a 

 thinner elastic sticky thread, out of which the snare is woven. The outer 

 part of the web forms the snare. The central part of the web usually con- 

 tains a shield of closely woven silk on which the spider may rest. Some orb 

 weavers live near one edge of the web, hanging suspended within easy reach 

 of a possible capture. In traveling over the outer part of the web the 

 spider uses the guy lines only, as otherwise it might destroy its own web. 

 Why? 



One of the commonest of the orb weavers is a large yellow and black 

 spider known as Argiope. Their webs may be found in almost any garden 

 or yard. 



Find such a web. Describe its location. How is it attached? How 

 many guy lines does it contain? Look for the central shield on which the 



A poisonous centiped from Texas. Half natural size. From photograph by Davison. 



spider rests. Do you find a "winding stair"? Notice the open area be- 

 tween the central home of the spider and the outer or spiral zone of the 

 web. This area, known as the free zone, gives opportunity for free move- 

 ment around the web, as the spider does not travel on the sticky outer 

 portion. 



Other Forms of Web. — Other forms of webs are seen in the wonderful nc^st 

 of the trapdoor spider which, after excavating a hole in the ground, lines 

 it with silk and then makes a lid of earth also lined with silk. Tliis lid is 

 closed by the spider after its retreat to the hole. Other spiders use the web 

 for bridge building. In this case a long single strand is spun which is 

 allowed to float off behind the spider into the air. This is flown like a 



hunter's BIOL. 17 



