May, 1920] Studies in Food of Spiders 249 



them was eating some other small spider, PhUodromous vulgaris, 

 most often being the victim. 



I have seen Argiope riparia and Ageletia ncevia occasionally 

 eating one of their own species or some other spider but this 

 practice as far as I have observed is not so common as is gen- 

 erally thought to be the case. One can pen a couple of spiders 

 of some species up in a box together and if one keeps them sup- 

 plied with food they live together peaceably. If food is not 

 supplied they take to the cannibalistic habit and the weaker 

 one becomes the victim of the larger. I had a Dolomedes 

 tenebrosus penned in a small box for sometime and neglected 

 to feed it for a few days. It became hungry and devoured the 

 contents of its own egg sac which it had been carrying around 

 for several days. In another box I kept two individuals belong- 

 ing to Lycosa avida. One of these was much larger than the 

 other but they got along very well for some time. One evening 

 I dropped a large fly between them and both of them jumped to 

 get it. The smaller one was the quicker and got the fly first, 

 but the larger spider was not to be outdone so he pounced on 

 the smaller one and killed it, and the fly besides, and ate the 

 fly and the head of his cage-partner. Since 83% of the food of 

 the spiders observed consisted of insects injurious to crops, I 

 think this spider should be considered of some benefit to the 

 agriculturist. It takes a toll of a few honey bees for the good 

 it accomplishes but in this case the percentage of honey bees 

 is not high, being only 5%. 



Argiope riparia Hentz. 



Argiope riparia, because of its large size and bright coloring, 

 is perhaps the best known of all of our common spiders. Where 

 this spider has been studied it has been more abundant than 

 any other spider except Agelena ncevia. The web is very large, 

 often being more than two feet in diameter. The web is either 

 vertical or a little inclined and the spider when at rest stations 

 itself in the center of the hub. It has the peculiar habit of 

 making a small ' ' clearing ' ' when about to make its web in thick 

 tall grass. This is done by drawing aside the grass around a 

 central point in which the web is to be made. In this way the 

 web is not so easily injured by tall grass swaying into it. And 

 again when insects become entangled in the web and attempt 

 to escape, they are less liable to be able to get hold of some- 



