ARTHROPODS. CLASS ARACHNIDA 



147 



small birds. These are almost instantly killed by the poison- 

 fangs, and are then carried to the burrow, where the juices 

 of the body are extracted. 



The trap-door spiders of the southwestern section of the 

 United States also dig tunnels, which they cover with a 

 closely fitting lid com- 

 posed of earth. Raising 

 this they come out in 

 search of insects, but if 

 sought in turn, they dash 

 into the burrow, closing 

 the door after them, and 

 holding it with such firm- 

 ness that it is rarely forced 

 open. If this should hap- 

 pen, there are sometimes 

 blind passage-ways, also 

 closed with trap-doors, 

 which jusually baffle the 

 pursuer. 



Finally, there are 

 among the thousand spe- 

 cies of spiders in the United States a considerable propor- 

 tion which construct no definite web. Many of these may 

 be seen darting about in the sunshine on old logs and 

 fences, often trailing after them a thread which may sup- 

 port them if they fall in their active leaping after in- 

 sects. 



139. Breeding habits. The male spiders are usually much 

 smaller than the females, and some species are only one- 

 fifteenth as long as the female and one one-hundredth of 

 its weight. They are usually more brilliantly colored, more 

 active in their movements, yet rarely spinning their own 

 webs and capturing their own food, preferring to live at 

 the expense of the female. At the breeding 'season the 

 males of several species make a most interesting display 



FIG. 87. Trap-door spider and burrow 

 ( Ctenizd). 



