THE AERIAL WEB SPINNERS 163 



debris, form the cobweb anathema of the neat housewife. One of 

 the most handsome and colorful members of the family is the black 

 widow, whose beauty, however, is marred by its unsavory reputa- 

 tion. A few theridiids have hard bodies ornamented with curious 

 spines; in others the abdomen is drawn out to amazing lengths. 

 Most are inveterate spinners, but a few curious types (Conopistha) 

 live in the webs of other spiders as commensals, and another group 

 (notably Euryopis) has forsaken a formal web for an errant life. 



Most of the theridiids have rather soft, light-colored abdomens, 

 oval or globose in form, and long, slender legs that lack spines. One 

 of their special features is the presence, on the tarsi of the fourth 

 pair of legs, of a line of enlarged, curved, and toothed setae that 

 form a distinct comb used to fling silk over the prey. In most of the 

 comb-footed spiders, the comb is strong and distinct, but in the 

 smallest ones it may be difficult to see, and in some others it has 

 become reduced to a few modified setae. Their relatively small 

 eyes are set close together in a group near the front of the head. 

 Sight enters their lives only to a limited degree, since they live in 

 dark places and become active chiefly at night. Some males are 

 mere pygmies beside their bulky mates, and there is often a marked 

 sexual dimorphism. The theridiids occur in great numbers in the 

 temperate and tropical zones; within the United States and Canada 

 several hundred different species representing about twenty-five 

 genera are found. Thus mention can be made of only a few that 

 typify the group, or are outstanding for peculiarities of habit. 



The snare of the comb-footed spiders (Text Fig. 5, B) is not the 

 simple mass of irregular lines that casual study would seem to indi- 

 cate. It has incorporated into its limits some interesting innovations. 

 A densely woven sheet of silk is often a feature, serving as a shelter 

 under which the spider retreats. Leaves and debris, or grains of 

 sand, may be used as building materials. One of the most interesting 

 homes is the bowl of the boreal Theridion zelotypum. Composed of 

 dried spruce needles or other plant parts sewed together with silk, it 

 provides a strong, waterproof tent beneath which the spider can 

 hide with its eggs and young. In some instances the theridiids 

 leave their spherical egg sacs suspended in the scaffolding of lines 

 in plain sight. 



On the outskirts of the web at the proper season may be seen 

 the mature males, which are received for the most part with kind- 

 ness during courtship and following mating. Males are killed oc- 

 casionally, but not with the regularity ascribed by popular belief. 



