134 SPIDERS 



on some projecting twig. Having fixed a sufficient number of 

 oundation lines in place she puts in the spokes of the wheel, 

 stretching the threads across the framework so that they all meet 

 in the centre. The hub of the wheel is next strengthened by a 

 few rings of silk which serve to bind the spokes firmly together, 

 and then, starting from this central point, the spider works in a 

 spiral scaffolding with the successive rings rather wide apart. 

 The most important part of the snare has now to be woven in ; 

 starting at the circumference, and working her way upwards, 

 she puts in the viscid spiral rings on which the capture of her 

 prey depends. The foundation lines, the spokes, and the scaf- 

 folding are of ordinary dry silk ; but the final rings are formed 

 with silk which is covered with a gummy secretion. As the spider 

 swings from point to point on her scaffolding she stretches this 

 thread, which is highly elastic, as tightly as possible, and at the 

 moment of fixing it to one of the radiating lines lets it go with 

 a snap. This causes the coating of viscid matter to form into a 

 number of tiny globules all along the thread, which, seen through 

 a pocket lens, has the appearance of a string of beads. The web 

 now being complete, the spider either takes her stand in the 

 centre or retires to a position close at hand, often under a shelter- 

 ing leaf, to await the reward of her labour. 



Some Orb-weaving Spiders ornament their snares with tufts 

 of flossy silk, while other species work in a broad ribbon of flossy 

 silk in a zigzag pattern between two of the spokes of the wheel, 

 like a winding staircase. The North American Orb- weaver (Argiope 

 cophinaria) finishes her snare in this way, and she also works in a 

 central shield behind which she sometimes takes her stand to 

 conceal herself from possible victims or enemies. 



Some of the snares constructed by spiders are marvels of 

 ingenuity. The Triangle Spider, Hyptiotes cavatus, makes a regular 

 spring trap. From one foundation line the spider draws four 

 radiating lines converging to a point. These are connected by 

 cross lines which are not of a sticky nature, but are fluffed and 

 teased out in the process of spinning. From the apex of the 

 triangle a line is carried to an object a little distance away, and on 

 this the spider takes up her position, back downwards, facing 

 her trap. She then hauls in the line until it is quite taut and 

 waits until a trembling of the thread tells her of the arrival of a 



