248 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
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 
Sanit ; trapped, and the spider should be particularly hungry, she will 
una as *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 
he 
Fic. 225. Insect entangled by Fic. 226. A mosquito cap- 
all the feet. 
Fic. 224. Mosquito 
entangled by strik- 
ing the net with 
full spread wings. 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 Orbweayer 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- 
of Pores ceive a spider, particularly if she be quite young or very hun- 
tian. gry. 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 
bs ss. x03) 
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