THE AERIAL WEB SPINNERS 189 



except for the bulk of the abdomen. It is among these orb weavers 

 that the male seems to run the greatest risk while courting, but he 

 has learned to reduce the danger by dropping on his dragline when 

 his attentions are evidently unwelcome. His long front legs are 

 usually armed with rows of spines that aid in holding the female, 

 and in keeping her at arm's length when she pursues him. With the 

 exception of the few species that have modified their ensnaring 

 habits, the typical orb weavers spin a circular web, but considerable 

 differences are found in the details of the orb and accompanying 

 retreats. 



The small, elongated species of Cyclosa (Plate XXIV), usually 

 about one fourth of an inch long, have conical humps at the end 

 of the abdomen. Through the center of their beautiful snares, fur- 

 nished with many radii and closely set spirals, often lies a stabilmen- 

 tum consisting largely of the remains of insects and debris tied 

 together with silk. The eggs are later added to the string. The 

 spider sits at the hub, bridging the space between the segments of 

 the string and blending so completely with it as to be practically 

 invisible. 



The webs of most orb weavers still maintain, at least in vestigial 

 form, the ancient mazes of their prototypes. In the labyrinth spider, 

 Metepeira (Plate 23 and Text Fig. 5, E), the maze has been retained 

 as a prominent, irregular net, which the spider uses as a base and in 

 which it hangs its leaf retreat and string of eggs. Many species occur 

 in the United States; they vary in size from one-fifth to one-half 

 inch in length. The orb web is usually complete, with several trap 

 lines leading from the hub to the retreat of the spider in the tangle. 

 The spiderlings use the labyrinth as a nursery web after they break 

 out of the egg sacs, and it is reported that they sometimes feed upon 

 small insects caught in the tangle. 



Several of these typical argiopids habitually spin incomplete orb 

 webs, entirely omitting the spiral lines and radii from a segment 

 equal to the space between two or three radii. This they accomplish 

 by spinning rounded loops, and swinging back and forth many times 

 instead of making complete circles. Associated with such snares is 

 a trap line, sometimes virtually bisecting the open sector but usually 

 in a different plane, that leads to a nearby retreat. The species of 

 Zygiella spin incomplete orbs of this type, but better known to 

 Americans are those of Aranea pegnia and A. thaddeus, which have 

 far wider distribution. The lattice spider, Aranea thaddeus, is about 

 one-fourth inch long and has a rounded abdomen of a pale, yellow- 

 ish color with darker sides. Its beautiful silken retreat is usually 



