ARTHROPODS. CLASS ARACHNIDA 137 
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 usually baffle the 
DETEORT Fia, 84.—Trap-door spider and burrow 
Finally, there are (Cteniza). 
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. 
133. 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 
