162 SPIDERS 



with the simultaneous destruction of the temporary spiral as it is 

 reached. Many orb weavers renew their webs, other than the 

 framework, daily, but renewal may be postponed if the spiders are 

 well fed or the weather unsuitable. 



The chief economic use of spiders' silk lies in the construction of 

 fine graticules for optical instruments. Cobwebs were used years 

 ago as dressings for wounds to staunch the flow of blood, for which 

 they were extremely effective. Moulds such as Penicillium were 

 sometimes added, perhaps foreshadowing the present-day use of 

 penicillin and other antibiotics. When several sheet-webs are 

 superimposed they form a fine transparent silk fabric on which 

 delicate and beautiful pictures were painted early in the nineteenth 

 century by an Innsbruck family named Burgman. They are 

 'exquisite examples of an art that now ranks as scarcely more than 

 a curiosity'. 



Food and feeding habits 



The food of spiders includes a variety of insects, woodlice, 

 myriapods, false-scorpions, harvest-spiders and other Arachnida. 

 Bristowe (1941),* who has discussed the subject at some length, 

 has shown that the potential food supply of different species varies 

 within wide limits. A hungry spider is liable to accept an insect 

 which it will reject when fully fed, thereby indicating that its dis- 

 taste is relative and not absolute. By their mode of life, their 

 hunting methods and the nature of their snares, different species of 

 spiders become adapted within wide limits to the capture of 

 particular insects and may refuse types to which they are un- 

 accustomed. Thus although Amaurobius spp. may investigate with 

 their legs a woodlouse thrown into their webs, they nearly always 

 retreat without harming it. Unlike Segestria senoculata, which will 

 attack a blade of grass drawn across its web, and normally eats 

 woodlice, A.ferox and A. similis will respond only to the vibrations 

 of a tuning fork, and will attack a woodlouse if a vibrating tuning 

 fork is placed on the web just beside it (Cloudsley-Thompson, 

 1956). 



Atypus affinis, the sole British representative of the sub-order 

 Mygalomorpha, burrows in the soil, but instead of making a trap- 

 door, it continues the silk lining of its burrow ab ove the ground as a 



