112 



NATURAL HISTORY OF ARTHROPODS. 



hind-feet, and let the bubble go. The water-spiders run about on water-plants, and 

 catch the insects which live among them. 



The simple nests and tubes that have been described are made by spiders, most of 

 which spin no other webs. The larger and better known cobwebs for catching insects 

 are made by comparatively few species. On damp mornings in summer the grass-fields 



Fig. 158. — Web of Agalena. 



are seen to be half covered with flat webs, from an inch or two to a foot in diameter, 

 which are considered by the weatherwise as signs of a fair day. These webs remain 

 on the grass all the time, but only become visible from a distance when the dew settles 

 on them. Fig. 158 is a diagram of one of these nests, supposed, for convenience, to be 



spun between pegs instead of grass. The 

 flat part consists of strong threads from 

 peg to peg, crossed by finer ones, which 

 the spider spins with the long hind-spin- 

 nerets, swinging them from side to side, 

 and laying down a band of threads at 

 each stroke. At one side of the web is 

 a tube leading down among the grass- 

 stems. At the top the spider usually 

 stands, just out of sight, and waits for 

 something to light on the web, when 

 she runs out and snatches it, and carries 

 it into the tube to eat. If anything too 

 large walks through the web, she turns 

 around, and retreats out of the lower 

 end of the tube. In favorable places 

 these webs remain through the whole 

 season, and are enlarged, as the spider 

 grows, by additions to the outer edges. 

 Similar webs are made by several house- 

 spiders, and are enlarged, if let alone, 

 tiU they are a foot or two feet wide, and 

 remain till they collect dirt enough to tear them down by its weight. 



Nearly all spiders that make cobwebs live under them, back downward ; and many 



Pig. 159. — Web of LinypMa marmorata. 



