SPIDERS 



167 



at their point of attachment. As they are drawn very taut, an 

 insect which blunders into one not only breaks the attachment but 

 may be lifted into the air where its struggles bring it into contact 

 with other viscid threads. The meshed webs of the Dictynidae and 

 some Uloboridae with their typical calamistrated threads have 

 already been mentioned. These threads entangle the legs of in- 

 sects very securely and enable the spiders to capture prey often 

 much larger than themselves. 



Fig. 37. Diagrammatic stages in the spinning of an orb-web. 

 (After Savory, 1952.) 



Finally, typical orb webs are made by the Tetragnathidae and 

 Argiopidae. During the daytime the garden spider Araneus dia- 

 dematus generally abandons the hub of its web and rests in its 

 retreat nearby, but towards evening it usually comes to the centre 

 and remains there until early morning when it constructs a new 

 web. Peters (1933) has shown that the prey is dealt with by means 

 of a series of chain reflexes. The struggles of a victim in the web 

 are the stimulus for a long bite and the taste experienced stimu- 

 lates the enshrouding of the prey. The silk bands provide a tactile 

 stimulus for the reflex of the short bite, which in turn produces a 

 stimulus for the carrying reflex: small insects are carried to the hub 



