COURTSHIP AND MATING 89 



graphing to the occupant of the web the arrival of the male. In 

 later stages a tactile stroking of the body precedes the coition. The 

 male web spinner has an advantage in that he can approach the 

 female at a distance and is not immediately vulnerable to her attack. 

 A hasty retreat follows notice from the female that he is unwel- 

 come. The whole routine of tweaking the threads, approaching the 

 female on the surface of the web, and further stimulating her at 

 close quarters, constitutes a tactile display of courtship equal in 

 interest to that of the long-sighted spiders. 



Among the web builders we find some females that are very 

 tolerant of their males and accept their advances eagerly. Some live 

 together quite amicably for weeks, and others are gregarious by 

 habit, spinning huge communal webs in which the sexes live in 

 seeming equality. Withal, there also exist in this group females 

 notorious for their aggressiveness, which are known to destroy their 

 males before or after the mating. Specialization in the orb weavers 

 has taken them along a path where there is a premium for vigorous 

 response to the touching of their snare by any interloper. The 

 spider hurls itself over its web and, by a remarkable exhibition of 

 trapeze artistry, quickly subdues and enswathes its prey. It is there- 

 fore not surprising that so finely trained an aggressor should occa- 

 sionally fail to recognize the advances of a male of her species. The 

 latter is in especial danger if the female is not fully adult, has already 

 mated, or is gravid. After the mating he is in great danger if he 

 tarries too long; it is then that he is most often killed. 



Among the web spinners are some that are more closely allied 

 to the long-sighted hunters than to their own group, and, except for 

 the silken sheet web over which they run in an upright position, 

 resemble the former in their courtship and mating attitudes. Males 

 of the Agelenidae are in most cases equal to the females in size, and 

 superior in agility. Agelena Pennsylvania a, the commonest grass 

 spider of the naevia group, moves upon the web of the female and 

 signals to her by tapping the silk with his legs and palpi. His ad- 

 vance is usually slow and measured until he is able to touch her 

 with his legs, whereupon he actively seizes her. In most instances 

 resistance is not strong; the male grasps her hind femora in his 

 chelicerae and carries her to the entrance of the silken tunnel, where 

 mating often occurs. He throws her on her side and, his head point- 

 ing in the opposite direction from hers, turns her over and applies 

 the palpi from either side. 



The tangled-web spinners (family Theridiidae) include many 



