388 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



of the beautiful paper nest. Now, in the act of reducing spider flesh to 

 pulp it is natural to suppose that a taste for such food might be ac- 

 quired (and, perhaps, it is even gratified) in sufficient strength to lay 

 the foundation, at least, for an insectivorous habit in the progeny. 



But our mud dauber does not feed her own larvae at all ; the far away 

 originals of her species could have had no reasonable origin for a faintest 

 suggestion of arachnophagous necessity in her progeny, and how then did 

 she begin her persistent harvesting of spiders? It is, perhaps, possible 

 to conceive that it may have come by the long, roundabout way of an 

 insect chewing hornet or rust red wasp, but whether it is worth while to 

 go so far to get so little, the advocates of the development theory must 

 consider. The point in which the author is here specially interested is 

 that the social wasps also are to be ranked with the enemies of spiders. 



V. 



It has been stated that all spiders are addicted to cannibalism, no 

 species scrupling to prey upon individuals of its own order. As a rule, 

 however, every species takes aranead prey, as it does insects, 

 ar ~ after its own characteristic modes. But the habit of cannibal- 

 ism has a peculiar manifestation in the case of several species 

 belonging to the Retitelarire. One of these is a beautiful California spi- 

 der, first sent to me by Mr. C. R. Orcutt, which is conspicuous by bright 

 metallic silver markings upon a black triangular body. It is a small 

 creature, but is evidently possessed of unusual cunning and ferocity. My 

 knowledge of its habits is received from Mrs. Eigenmann, who forwarded 

 to me living examples of both sexes. I have named the species (in lit- 

 teris) Argyrodes piraticum. 1 The spiders were established on what seemed 

 to be foundation lines of their own, which were attached to the broad 

 foundation lines of a large orbweb of a species of Epeira. In one CM-V 

 an Argyrodes was found in the act of preying upon a large Orbweaver 

 which she had encased within a silken enswathment and trussed up on 

 its own web. It seemed remarkable to the observer that the 

 little silvery spider could slay and eat a creature so much larger 

 g . , than itself, and, indeed, nothing short of actual observation would 



justify belief. My informant has found this pirate spider upon 

 the snares of Gasteracantha, Argiope argenteola, and Zilla x-notata, as 

 well as upon orbs of various species of Epeira. It takes its station quite 

 habitually upon the outskirts of the snares of these Orbweavers, from 

 which point it makes its raid upon the lawful owner of the web, and 

 perhaps, also, as Mrs. Eigenmann thinks, feeds upon the excess of insects 

 which may often be found adhering in considerable numbers to the viscid 

 portions of the orb. 



1 It has probably been described, but I cannot identify it. 



