340 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Bowing 

 Orbs. 



In certain species the trapline consists of several threads, as, for exam- 

 ple, in Epeira labyrinthea. In other species, where a single trapline is 

 the rule, the same habit will be sometimes observed, as, for ex- 

 Multiplex .j,-)„,ig jj-j ^j^g case of Zilla, whose trapline becomes a strangely 

 'complicated series of threads. (See Chapter VIII. , Fig. 118.) 

 Labyrinthea connects the central portion of her orb with the silken dome 

 or leafy shelter within her maze of intersecting lines, by a series of straight 

 lines sometimes quite numerous. These make a little bridgeway between 

 the tent and the orb. When the spider is within the tent the feet are 

 reached beyond the borders and grasp at various points these lines. 

 Sometimes the lines are twisted into a strong and single thread, either ac- 

 cidentally or by the voluntary 

 action of the spider. 



When one takes a side 

 view of the orb (see Fig. IIG, 

 page 138) he almost invaria- 

 bly finds the centre 

 drawn inward and 

 upward towards the 

 spider's retreat, thus causing 

 all the radial lines to bow 

 inward or toward one anoth- 

 er. In this position the snare 

 in its general outline has a 

 striking resemblance to that 

 of a Hay spider when it has 

 been bowed by its proprie- 

 tor in the manner described 

 and illustrated at Fig. 190, 

 I)age 19G. Epeira triaranea 

 has the same habit of bowing her web upward and inward towards her 

 den, and, indeed, such is the case with some other species ; necessarily, 

 more or less of this bowing of the orb must result from the habit of 

 holding the trapline taut. But in the case of Labyrinthea the bowed 

 condition of the web is more striking, I think, than in any other spe- 

 cies with whose spinningwork I am acquainted, and is so noticeable that 

 the most casual observer may see it. 



We come now to the use of the trapline as it is even more highly 

 specialized in the habit of the Triangle spider. Here the line serves not 

 only the purposes common to the species already described, but 

 Hypti- becomes a real instrument in the spider's hands for springing 

 rj, ,. her net. Such Orb weavers as Epeira strix and Epeira trifolium, 

 when they are drawing their traplines taut, necessarily leave a 

 little slack line between the point of seizure by the fore claws and the 



Fig. 331. The Stellate spider trapping with the scant 

 remnants of a snare. 



