May, 1920] Studies in Food of Spiders 219 



Some of the Therididae eject on the insect liquid silk from 

 their spinning tubes and I suspect, although I have not proven 

 it, that this liquid silk has a dissolving effect on the chitin. 

 Theridium tepidarionim, one of the common Therididae, destroys 

 many beetles in barns and cellars and the chitinous parts of 

 the insects seem to disintegrate in a short time after it gets 

 into the spider web. 



There are many remarkable color adaptations, but since 

 we believe they are mostly adaptations for protection and not 

 food getting, they will not be discussed here. 



GENERAL DISCUSSION. 



In determining the economic status of spiders several 

 factors should be taken into consideration. The principal 

 ones being the number of spiders of any given species on a 

 certain area, the number and size of the insects used as food, 

 and the economic status of the insects fed upon. 



To gain definite information on these things has been the 

 object sought in these observations. Although it is of necessity 

 rather fragmentary, it is hoped that the records will show to 

 some extent the part that these creatures play in the balance 

 of nature. Besides the species of which records are given, 

 many more were found in the same localities, but only the more 

 numerous ones were studied. 



Many different spiders of widely separated families may be 

 found living together within a few feet of each other. But 

 each species usually has a preference for a certain kind of con- 

 dition, as Argiope riparia makes its web preferably in tall 

 grass and weeds. 



One example of the diversity of species in a limited area 

 will be given. I found on and around a rose bush (Rosa 

 Carolina) about 20 feet long and 19 feet wide, the following 

 species : 



Two individuals of Metepeira lahyrinthea. 

 Eight individuals of Epeira domiciliorum. 

 One individual of Epeira gigas. 

 Eleven individuals of Epeira trifolium. 

 Three individuals of Argiope riparia. 

 Eight individuals of unidentified species. 



