THE RAFT SPIDER. 381 



leaves and similar substances, which it gathers into a rough ball, 

 and fastens with silken threads. On this ball the Spider sits, 

 and allows itself to be blown about the water by the wind. 

 Apparently, it has no means of directing its course, but suffers 

 its raft to traverse the surface as the wind or current may 

 carry it. 



There is no lack of prey, for the aquatic insects are constantly 

 coming up to breathe the air ; and although they may only 

 remain on the surface for a second or two, the Spider can seize 

 them before they can gain the safe refuge of the deeper water. 

 Then there are insects, such as the gnat, which attain their 

 wings on the surface of the water, and can be taken by the 

 Spider before they have gained strength for flight. Also, there 

 are insects which habitually traverse the water in search of prey, 

 and which are themselves seized by the more powerful and 

 equally voracious Spider. More than this, moths, flies, beetles, 

 and other insects, are continually falling into the water, and 

 these afl'ord the easiest prey to the Raft Spider, who pounces 

 upon them as they vainly struggle to regain the air, and then 

 carries them back to its raft, there to devour them in peace. 



The Spider does not merely sit upon the raft, and there 

 capture any prey that may happen to come within reach, but 

 when it sees an insect upon the surface, it leaves the raft, runs 

 swiftly over the water, secures its prey, and brings it back to the 

 raft. It can even descend below the surface of the water, and 

 will often crawl several inches in depth. This feat it does not 

 perform by diving, as is the case with the water spider, but by 

 means of the aquatic plants, down whose stems it crawls. Its 

 capability of existing for some time beneath the surface of the 

 water is often the means of saving its life ; for, when it sees an 

 enemy approaching, it quiedy slips under the raft, and there lies 

 in perfect security until the danger has passed away. 



There is, living in the same localities, a closely-allied species, 

 the Pirate Spider (Lycosa piratica), which has similar habits, 

 chasing its prey on the water, and descending as well below 

 the surface. It does not, however, possess the power of making 

 a raft. 



