138 



GENERAL ZOOLOGY 



Many spiders build circular webs of silk, in which they 

 capture insects to suck their blood. A common species of 

 garden spider (Miran'da auran'tia) is shown in Fig. 75. 

 The spider first spins a line across the space where the web 

 is to be and then attaches near its center other threads, 



which it carries to dif- 

 ferent points, making 

 the radiating founda- 

 tion lines of the web. 

 These lines are all dry 

 and inelastic. Concen- 

 tric spiral lines of an 

 adhesive nature are 

 then added, the hind 

 legs being used to place 

 the threads. An oval 

 cover of silk is spun in 

 the center. Beneath 

 this, or in a folded leaf 

 at the side, the spider 

 lurks in watch for its 

 prey. A zigzag band of 

 white silk crossing the 

 center is usually added 

 to strengthen the web. 

 When an insect is cap- 

 tured the spider rushes out, and if there is any danger of 

 the escape of the prey it is deftly wound with more silk 

 till its struggles have ceased. If it proves to be a wasp or 

 other dangerous captive, or if it is too big to be safely man- 

 aged, it is often assisted to escape by the spider's cutting 

 the web, which is then repaired for another victim. 



Like the click beetles and many others of the Coleoptera, 

 this spider when alarmed has the habit of dropping to the 



Palpus 



Chelicera 



,Cephalothorax 



Breathing organ 



Openings to 

 {reproductive organs 



|- Abdomen 

 I - - - Fourth leg 

 y ■ Trachese 

 -Spinnerets (3 pairs) 



Fig. 74. External anatomy of a spider, 

 Epeira vulgaris. (Enlarged) 



After Emerton 



