3l8 WILLIAM MORTON BARROWS. 



located twenty-four hours later while the females often live for 

 weeks in the same place, repairing the web every evening but not 

 altering it materially. 



In crawling across the web the spider always follows a radiating 

 strand or at the edge of the web, one of the guy strands, and 

 places its feet on the radii or on the junctions of the radii and 

 spiral threads where the latter hold no sticky materials. The 

 front feet are usually placed on the same radiating strand but 

 the second and third pairs may be spread out on the two ad- 

 joining strands. It is possible for the spider to crawl rather 

 swiftly along a single strand for a considerable distance, all eight 

 feet using the same thread. In crossing the web the spider usually 

 leaves behind a dragline which may remain across the web, 

 adhering to it after the spider has returned to the center Some 

 individuals on the other hand when they reach the edge of the 

 web swing free, held only by the drag line up which they climb 

 in returning to the center. Occasionally one finds both methods 

 employed by the same individual. Most spiders are not skilful 

 enough to cross the web several times without tearing out or 

 snagging several of the segments of the spiral thread. When the 

 web is violently disturbed the spider usually retreats to a niche 

 or corner (the retreat) and remains there motionless unless again 

 disturbed. Some individuals remain in the retreat instead of at 

 the center of the web. When this is done one forefoot is placed 

 on the trapeline leading to the hub and any activity of the web 

 such as that produced by an entangled insect sends the spider 

 like a flash down to the web. In this connection another fact 

 may be noted; a spider outside the center of the orb always 

 returns to the center, takes the normal position and then orients 

 before it finds an entangled insect. This might be explained as 

 due to the difficulty of crossing the web by any other path than 

 by the radii. However, the inability to orient accurately in any 

 other position than the center gives a clue to a more probable 

 explanation. Individuals of the species Epiera sclopetaria will 

 eat nearly any insects which happen to become entangled in the 

 web. The food of those studied inside the screened porch con- 

 sisted almost entirely of rather large flies of the genera Musca, 

 Sarcophaga, and Lucilia. It is in the snaring of these flies that 



