THE HUNTING SPIDERS 197 



they can leave their crowded quarters. The mother then bites open 

 the sac at the seam, and within a few hours a whole brood of tiny 

 spiderlings has climbed upon her back and huddled there in a mass 

 (Plate XXV) . The cluster will completely cover her abdomen and 

 much of her carapace, and very often is composed of more than 

 one layer of spiderlings. It seems to be true that the mother must 

 open the egg bag, and that without her assistance the babies will 

 often perish. 



During the time of carrying the young, the mother engages in 

 normal hunting activities, and her children must accommodate 

 themselves to a strenuous life. She will run with great speed when 

 pursuing or being pursued, turn to defend herself when cornered, 

 and during all these wild gyrations the spiderlings cling to her back. 

 When brushed off, they quickly crawl back upon their perch if 

 they have the opportunity. During this period they do not take 

 food, a fact that has led to considerable speculation as to how they 

 are able to survive. By some they were thought to derive energy 

 from the sun and air. However, adult spiders are notorious for 

 their ability to go without nourishment, and the spiderlings are 

 equally tolerant. Their bodies are provided with a food supply, 

 and this is adequate to maintain them until they start feeding. While 

 they are riding on their mother's back, which may be for a full 

 week, they are merely biding their time until the next molt, after 

 which they will leave to take up separate lives in the grass, and will 

 begin their own hunting activities. The spiderlings do drink water 

 during their stay, and probably find a sufficient supply in the dewy 

 film that often covers them fct night. They have been observed to 

 move to water and take their fill when the mother stops to drink, 

 then clamber back on her abdomen. 



The success of the wolf spiders in surviving is unquestionably 

 due in part to the initial protection given the eggs and young by 

 the mother; that is to say, by maintaining a vigil over the sac, by 

 carrying it always with her, by seeing that it is broken open and 

 that the young are permitted to emerge. Thereafter, however, the 

 clustered spiderlings seem to remain with her through their in- 

 clination rather than hers. She pays little attention to them, and 

 abandons them if they fall off and cannot reach her of their own 

 initiative. 



It is possible to give in this brief section only a glimpse into the 

 lives of a few American wolf spiders. A wealthy fauna made up 



