48 CHARLES DARWIN 



of a quite small spider ; and this spider, instead of cutting 

 the web, most perseveringly continued to entangle the body, 

 and especially the wings, of its prey. The wasp at first 

 aimed in vain repeated thrusts with its sting at its little 

 antagonist. Pitying the wasp, after allowing it to struggle 

 for more than an hour, I killed it and put it back into the 

 web. The spider soon returned; and an hour afterwards I 

 was much surprised to find it with its jaws buried in the 

 orifice, through which the sting is protruded by the living 

 wasp. I drove the spider away two or three times, but for 

 the next twenty-four hours I always found it again sucking 

 at the same place. The spider became much distended by the 

 juices of its prey, which was many times larger than itself. 



I may here just mention, that I found, near St. Fe Bajada, 

 many large black spiders, with ruby-coloured marks on their 

 backs, having gregarious habits. The webs were placed verti- 

 cally, as is invariably the case with the genus Epeira: they 

 were separated from each other by a space of about two 

 feet, but were all attached to certain common lines, which 

 were of great length, and extended to all parts of the com- 

 munity. In this manner the tops of some large bushes were 

 encompassed by the united nets. Azara 10 has described a 

 gregarious spider in Paraguay, which Walckenaer thinks 

 must be a Theridion, but probably it is an Epeira, and perhaps 

 even the same species with mine. I cannot, however, recol- 

 lect seeing a central nest as large as a hat, in which, during 

 autumn, when the spiders die, Azara says the eggs are de- 

 posited. As al! the spiders which I saw were of the same 

 size, they must have been nearly of the same age. This 

 gregarious habit, in so typical a genus as Epeira, among 

 insects, which are so bloodthirsty and solitary that even the 

 two sexes attack each other, is a very singular fact. 



In a lofty valley of the Cordillera, near Mendoza, I found 

 another spider with a singularly-formed web. Strong lines 

 radiated in a vertical plane from a common centre, where the 

 insect had its station; but only two of the rays were con- 

 nected by a symmetrical mesh-work ; so that the net, instead of 

 being, as is generally the case, circular, consisted of a wedge- 

 shaped segment. All the webs were similarly constructed. 



10 Azara' s Voyage, vol. i. p. 213. 



