114 



NATURAL HISTORY OF ARTHROPODS. 



them, the turns of the spiral being as far apart as the spider can conveniently reach. 

 She climbs across from one ray to the next, holding her thread carefully with one of 

 the hind-feet, till she gets to the right point, and then turns up her abdomen, and touches 

 the ray with her spinnerets, thus fastening the cross-thread to it. The figure shows her 

 in this position. When this spiral has been carried to the outside of the web, the 

 spider begins there another and closer one, of thread of a different kind. While the 



first thread was smooth, the latter 

 is covered with a sticky liquid, 

 which soon collects on it in drops, 

 and makes it adhere to anything 

 that touches it. After going 

 round a few times, this spiral 

 would cross the one that was 

 spun first if the spider would 

 allow it to; but, as she comes 

 to the old spiral, she bites it 

 away. By beginning thus at the 

 outside, the spider is able to cover 

 the whole web with adhesive 

 threads, and, without stepping 

 on them, take her usual place in 

 the centre. She usually is care- 

 ful enough to spin beforehand a 

 thread from the centre to her nest, 

 and sometimes stays there, with 

 on foot on the thread, so as to feel if anything is caught in the web. When she feels a 

 shake, she runs down to the centre, feels the rays to see where the insect is, and runs 

 out and seizes it. We have described the web as conssisting of one regular spiral; but 

 this is seldom the case. It is usually wider on one side than the other, or below than 

 above, where outside the spirals are several loops going partly round the web. The 

 web of Zilla consists entirely of such loops going three-quarters round the web, and 

 returning, leaving a segment without any cross-threads, in which is the line from the 

 centre to the spider's nest. The web of Nephila plumipes also consists of loops run- 

 ning round about quarter of a circle ; and in this web the smooth cross-lines which ai'e 

 first spun are not removed, but remain after it is finished. 



The round-web spiders repair their webs by tearing out a dirty, tangled piece, and 

 putting a new one in its place. Wilder says that Nephila plumipes tears off and 

 replaces half the web at one time. Epeira vulgaris often takes away an old web, and 

 puts a new one in the same place, tearing down the old in pieces, and putting in the 

 rays of the new as it goes along. The spider walks on the nearest sound thread, and 

 gathers in with her front-feet as much old web as she can tear off, and rolls it up with 

 her palpi and mandibles into a ball. As she walks along, gathering up the old web in 

 front, she at the same time spins a new thread behind, and, when she gets to a suitable 

 place, makes it fast as one of the rays of the new web. The common story has it, that 

 the spider eats the old web. She certainly gathers it up in her mouth, and some- 

 times throws it away at once, but at other times sits and chews it a long time, with 

 apparent pleasure. 



Various attempts have been made to use the silk of spiders, and chiefly that of the 



Fig. ) 61.— Web of Zilla. 



