INSECTS AND THEIR NEAR RELATIVES 



13 



Family Uloborid^ 

 The Hackled-band Spiders with regular webs 



We have already described the ribbon-like threads, or hackled-bands 

 of the dictynids (p. 12), and the curious organs called cribellum and 

 calamistrum, by which these curled threads are made (p. 8). Similar 

 organs and a similar habit are possessed by the spiders of the family 

 Uloboridae. These spiders, however, make webs which are regular in form. 

 There are only two genera belonging to this family in the United States; 

 but as the webs made by these are very different, we will describe both. 



The triangle spider, Hyptiotes cavatus. — This spider is common all 

 over New England and the Middle States, and has been found as far to 

 the Southwest as Texas. Its web is most often found stretched between 



Web of triangle spider. 



the twigs of a dead branch of pine or spruce. At first sight this web 

 appears like a fragment of an orb web (Fig. 28); but a little study will 

 show that it is complete. The accompanying figure, from a photograph 

 of a web of the triangle spider spun between two dead twigs of a pine 

 tree, illustrates the form of the web. It consists of four plain lines 

 corresponding to the radiating lines of an orb web, and a series of double 

 cross lines, which are spun by the cribellum and calamistrum. From the 

 point where the radiating lines meet a strong line extends to one of the 

 supporting twigs. Near this twig the spider rests, pulling the web tight 

 so that there is some loose line between its legs, as shown in the enlarged 

 figure. When an insect becomes entangled in one of the cross lines, the 

 spider suddenly lets go the loose line so that the whole web springs for- 

 ward, and the insect is entangled in other cross threads. The spider then 

 draws the web tight and snaps it again. This may be repeated several 

 times before the spider goes out upon the web after its prey. 



