216 The Ohio Journal of Science [Vol. XX, No. 7, 



by Tegenaria derhami. Out on the grass in a dewy summer 

 morning one can see hundreds of flat sheet-hke webs which 

 belong to the Agelenid^. Pholcus phalangiodes makes an irreg- 

 ular web in cellars and packing houses. On flowers one can 

 often flnd the small crab spiders with their forelegs extended, 

 waiting for some unwary insect to fly or walk into the trap. 

 In summer and fall Argiope riparia and Argiope trifasciata 

 make their large vertical orb webs in weeds, tall grass and 

 herbaceous plants. In bushes one is likely to find Aranea 

 trifoHum and Metepeira labyrinthea, both of which are orb 

 weavers. If you pull off the bark from some old log, you may 

 find Dolomedes tenebrosus. Lift up a stone and perhaps you will 

 find Lycosa avida or some other wandering spider. Late in the 

 fall Epeira gigas builds its web in bushes and far up in the 

 trees. Moss and dead leaves are alive with small spiders. Look 

 along an old rail fence, on top of fence posts or pull off the bark 

 of a stump and you will probably find Phidippus audax, 

 one of the jumping spiders. 



In short, spiders are widely distributed, have a great variety 

 of habits, and are adapted to various conditions. The distri- 

 bution of spiders depends mainly on the method of capturing 

 their food and the distribution of insects. Those spiders which 

 have adopted the web as a means of capturing food have 

 gained supremacy over non-netbuilding species in point of 

 numbers. Spiders likely first used the silk only for making 

 cocoons and egg cases. The web was probably developed first 

 by those species which live in holes and lined the entrance with 

 silk for protection. This may have developed later into a flat 

 web or a flat web with a retreat at one end. From this simpler 

 type we get a great diversity in web building. The ability to 

 make silk and use it for a variety of purposes is certainly the 

 important factor which has made spiders the most numerous 

 and widely distributed order of the Arachnida. 



The "ballooning habit" has enabled spiders to cross long 

 stretches of water and become established on isolated oceanic 

 islands; and to cross arms of the sea from one continent to 

 another. It has also enabled them to cross elevations of land 

 and become widely distributed which would be impossible were 

 it not for the production of silk. The main use to which this 

 silk is put, however, is in food getting and it is likely that it was 

 from this necessity that the habit arose. 



