S 6 
THE STUDY OF INSECTS. 
downwards, usually near the center of the net ; others have 
a retreat near one edge of the net, in which they hang back 
Fig. 41.—Partially completed web of Epeira. 
downwards. While resting in these retreats they keep hold 
of some of the lines leading from the net, so that they can 
instantly detect any jar caused by an entrapped insect. 
When an insect in its flight touches one of the turns of 
the sticky line, the line sticks to it; but it stretches so as to 
allow the insect to become entangled in other turns of the 
line. If it were not for this elasticity of the sticky line, most 
insects could readily tear themselves away before the spider 
had time to reach them. 
In making its web an orb weaver first spins a number of 
lines extending irregularly in various directions about the 
place where its orb is to be. This is the outer supporting 
framework. Often the first line spun is a bridge between 
two quite distant points. This is done as described on p. 25. 
Having a bridge across the place where the web is to be, it 
is an easy matter for the spider to stretch its other lines 
where it wishes them. I11 doing this it fastens a thread to 
one point, and then walks along to some other point, spin- 
