12 



THE STUDY OF INSECTS 



Fig. 26. — 

 Curled thread of 

 a Dictynid, en- 

 larged. 



the framework of their orbs of dry and inelastic threads, and attach to 

 this framework a thread which is sticky and elastic; while most spiders 

 which make irregular webs use only one kind of silk. There are, how- 

 ever, certain species of irregular web-weavers which use two kinds of 

 silk. One of them is a plain thread like that spun by other spiders, and 

 the other is a peculiar ribbon-like thread or band with curled threads 

 running through it. This ribbon-like band with its curled threads we 

 have called the hackled-band. 



The hackled-band weavers represent 

 two families, one of which makes irregu- 

 lar webs; the other, those which are of 

 definite form. The first of these is the 

 Dictynidag. 



The hackled-band is made in the same 

 way by both families. It is composed of 

 silk spun probably partly from certain of 

 the spinnerets and partly 

 from the cribellum (page 8); 

 and is combed into its pecul- 

 iar form by means of the 

 comb of stiff hairs, the cala- 

 mistrum, which is borne by 

 the metatarsus of the hind 

 legs (see page 8). In mak- 

 ing the hackled-band the spider turns one 

 of its hind legs under the abdomen so 

 that the calamistrum is just under the 

 spinnerets and makes a rapid combing 

 motion. By the rapid combing motions 

 of the hind legs the calamistrum finally 

 combs out from the spinning-tubes a 

 flat-thread and at the same time tangles 

 through it some curled threads; but it is 

 difficult to determine just how the 

 hackled-bands are given their charac- 

 teristic form and the whole process is 

 not well understood. 



This band of tangled or curled threads 

 is easily seen in the webs of these spiders, 

 being wider than the ordinary threads 

 and white in color. In old webs it becomes conspicuous by the large amount 

 of dust which it collects. Figure 26 shows the appearance of this band when 

 magnified, and the way in which it is attached to the plain threads. 



Our more common dictynids make webs of various shapes, on fences, 

 under stones, in holes in rotten logs, and on plants. These webs are 

 especially common among the flowers of golden-rod and other plants 

 having clusters of small flowers (Fig. 27), and exhibit a slight degree of 

 regularity. 



Fig. 27. — Web of dictynid. 



