The Life of Spiders 



VI.— THE TYPES OF WEBS OF SPIDERS 



The snares or webs of different spiders differ greatly in 

 structure. An imperfect classification can be made which will 

 indicate in a general way these differences; but the various types 

 are connected by intermediate forms; and in some cases, a spider 

 makes a composite web, one that includes two parts representing 

 two types of webs. The following classification indicates the 

 principal types of webs and will serve to define the terms applied 

 to them in the later portions of this book. 



Irregular nets. — The maze of threads extending in all direc- 

 tions that is built by the domestic-spider, Theridion tepidariorum 

 (Fig. 322) is a good example of an irregular net. Most members 

 of the Theridiidae and some other spiders spin webs of this type. 



Sheet-webs. — The most familiar example of a sheet-web is 

 that of Linyphia phrygiana (Fig. 408). Here the principal part 

 of the web consists of a more or less closely woven sheet extended 

 in a single plane and consisting of threads extending in all direc- 

 tions in that plane with no apparent regularity of arrangement. 



Funnel-webs. — The principal part of a funnel-web is sheet- 

 like in structure; but webs of this type differ from the true sheet- 

 webs in having a tube extending from one edge; this tube leads 

 to the retreat of the spider or serves as a retreat. The web of 

 the common grass-spider, Agelena ncevia (Fig. 662) illustrates 

 well this type. Frequently a very loose irregular net is spun above 

 the sheet of a funnel-web; this impedes the flight of insects and 

 causes them to fall upon the sheet where the spider, rushing from 

 its retreat, can capture them. 



Orb-webs. — The characteristic feature of an orb-web is that 

 the central portion, the part lying within the supporting frame- 

 work, consists of a series of radiating lines of dry and inelastic 

 silk which support a thread of viscid and elastic silk. Different 

 webs of this type vary greatly in structure; the principal variations 

 are the following: 



In the more symmetrical of the orb-webs the viscid line 

 extends throughout the greater part of its length as a spiral line 

 although near the outer edge o" the orb it is looped back and 

 forth a few times on the lower side of the web. The web of 

 Aranea frondosa (Fig. 186) is an excellent illustration of this kind 

 of a web. Such webs are termed complete orbs. 



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