May, 1920] Studies in Food of Spiders 239 



Epeira foliata was studied in two situations, the one along a 

 fence and the other on a house. They were watched all summer 

 upon the house where they were especially abundant. Early 

 in the summer I counted one hundred and sixty-nine individuals 

 on this one house. Most of them were near the ground, around 

 the windows, spouting and porches, but some of the smaller 

 ones were along the side of the house on the second story. 

 I counted them frequently and found the number varied but 

 slightly until the young began to hatch, late in the summer. 

 The number increased to several times the one hundred and 

 sixty-nine individuals, but the young were so small that it 

 was impossible to count- them accurately. However, I counted 

 as many as five hundred individuals. 



One would naturally suppose that the house fly, Musca 

 domestica, would be the insect most often eaten in such a 

 location and such was the case. Several half -grown spiders 

 constantly made their webs in a bed of geraniums where they 

 did good service in destroying a green aphid which infested 

 these plants. The number that was used as food was but a 

 small per cent of the number that was destroyed by becoming 

 entangled in the web. Toward the close of the summer there 

 were not very many of these aphids to be found. Although 

 other factors may have entered to some extent into their exter- 

 mination, I think it was largely due to these spiders. Besides 

 these insects and a few moths, other insects flew into their 

 webs occasionally. 



Excepting the gnats and midges destroyed, because it was 

 impossible to count them, the insects destroyed are rated as 

 follows : 



85% consisted of Musca domestica; 5% consisted of Aphids; 3% con- 

 sisted of Lepidoptera; 7% all other insects. 



I tried to make this spider eat the common firefly, Photinus 

 pyralis, but never succeeded in getting one to try it. I think 

 this may be due to the bitter taste this insect is supposed to 

 have. 



Epeira trifolium Hentz. 



The Shamrock spider as this one is sometimes called is one 

 of our largest spiders and also one of the most beautiful ones. 

 This spider matures late in the summer and has a compar- 

 atively short feeding period since they all die before winter. 



