248 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



I. 



In this position, when an insect strikes a snare the impact as well as 

 subsequent struggles set the web into violent agitation, which is at once 

 communicated to the spider. Her conduct will be largely determined by 

 the degree of agitation. Evidently the weight and size of the insect, and, 

 therefore, its ability to defend itself, are gauged by the force of the agita- 

 tion. If the insect appears to be a small one, or thoroughly 



Insect trapped, and the spider should be particularly hungry, she will 



Entangle- V . ' ,. , , ,- o r -i T? 



, rush immediately upon her victim. Ordinarily, however, the 



action is different. At the first signal, the spider will turn in an 

 attitude of great muscular tension, as though to get the direction of the 

 movement. She will often make a sharp pull, the whole body moving with 

 muscular excitement. Sometimes only the fore legs will be thus twitched. 

 Then a movement will be made toward the fly, which is conducted rather 

 cautiously and at several stages, the spider meanwhile jerking the radii 

 leading directly to the entangled insect. At each pause two or three quick 



FIG. 224. Mosquito 

 entangled by strik- 

 ing the net with 

 full spread wings. 



FIG. 225. Insect entangled by 

 all the feet. 



FIG. 226. A mosquito cap- 

 tured by several feet. 



jerks are made. Sometimes, however, for various reasons, but chiefly 

 through excess of caution, no doubt, she will fail to make any movement 

 at all, and leave the insect to struggle until it is exhausted, in which case 

 it may either be seized and eaten, or cut from the snare and thrown away. 

 The Orbweaver is not infallible in its ability to determine the charac- 

 ter of the agitation. Sometimes the deft tickling of the web will produce 



a movement so much like the agitation of an insect as to de- 



ccuracy ce ^ ye a g pid er) particularly if she be quite young or very hun- 



tion S rv - A touch upon a dry insect hanging in an empty web once 



drew to the spot a young spider from an adjoining snare. It 

 came straight to the point, as though directed by the agitation of the 

 neighboring web, thus showing a sense of direction, and ability to deter- 

 mine the originating points of the movement; but also showing the fact 

 that it was liable to be deceived as to the character of the movements of 

 a living insect. Once, while observing an Epeira vertebrata, a small insect 

 fell into the web. The spider ran towards it, seized it, and carried it to 

 the centre. While feeding, two bits of wood from an overhanging vine 



