212 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Argiope's 

 Young. 



the cocoon is a short hollow tube. Just below this tube on the inside 

 is hung a funnel shaped silken cap, which is attached above to a strong 

 silken cord composed of numerous fibres, which cord passes up- 

 Egress of wan i through the hollow stem, sometimes forming an outward 

 attachment to some external object. It would not be a diffi- 

 cult task for the young Argiopes to work their way between 

 the inner wall of the cocoon case and this cap above described, and so 

 along the cord and out into the air through the pedicle. If Mrs. Treat's 

 observation should be established as a common habit, it would, of course, 

 account for the fact that Professor Wilder found so many of these co- 

 coons without any external opening. Simply, the spiders had crawled 

 out through the pedicle ; but I believe this is not common. 



In the case of many cocoons spun by Epeira, and, indeed, by Orb- 

 weavers generally, there always is a selvage uniting the upper to the 

 lower portions of the outer case. As the spiders grow and the 

 period for egress approaches, this selvage appears to open, a 



The 



, , 



result which is perhaps due in large part to the influence of 

 weather and time in loosening the tension of the threads which 

 close the edges of the parts. Through this open selvage the spiders are 

 enabled to escape with comparative ease. Even were there no relaxing 

 of tension in the uniting threads, it would be easier for the spiderlings 

 to cut their way out from this part of the cocoon than through the un- 

 broken parts. A reference to several of the cocoons described in Chap- 

 ter V. will show this. 



It remains to be determined whether the mother in some species may 

 not be an active agent in delivering or aiding the deliverance of the 

 brood. Emerton once noticed a small Theridium gnawing at its 

 soft cocoon, and found that one side had in this way been made 

 much thinner than the remaining parts. He placed the spider 

 with her cocoon in a bottle, where he could watch her. She 

 soon recommenced the biting, and kept it up during the re- 

 mainder of the day. The following night the young came out. Of course 

 such a habit could only appear among those species that brood or watch 

 over their cocoons until the young are hatched, or among those who, like 

 various Theridioids and such Orb weavers as the Labyrinth and Tailed 

 spiders, make several cocoons and string them within their snares. As 

 most cocoons are abandoned by the mother immediately after spinning, 

 the enclosed young must escape without maternal aid. 1 



Menge observes that the warm rays of the spring sun awaken the germ 

 of the eggs, and by the time Mother Nature has provided a plentiful supply 

 of flies and mosquitoes, the young hatch. It is a peculiarity of spiders 

 that they do not leave the egg nest at once, but remain until legs, palps, 



Deliv- 

 ery by 

 Mother 

 Aid. 



1 "Structure and Habits of 



." ],a-r 104. 



