No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 



97 





Fig. 9. — Acrosoma rugosa. Left-hand figure 

 female, right-hand figure male (fromEmerton). 



uous, but in connection with its irregular shape and its way of 

 hanging motionless in the web it had the opposite effect. 



We have no reason to suppose that the class represented in 

 rugosa is like that touched upon by Poulton, in which very 

 protectively colored larvte 

 suddenly assume a terri- 

 fying aspect on the near 

 approach of an enemy; 

 still they do enjoy a kind 

 of double protection. 

 They are inconspicuous, 

 and thus likely to escape 

 attack, but in case they 

 are attacked they have 

 still the advantage of 

 being quickly rejected. 

 This experience cannot be as fatal to them as to the soft and 

 thin-skinned larvse. Their hard covering and projecting spines 

 would protect them to such an extent as to give them a fair 

 chance of surviving. 



In one respect the inconspicuous Gasteracanthidge have a 

 decided advantage over their bright colored relatives. The 

 birds, indeed, avoid the conspicuous ones, but their brilliancy 

 serves to attract another enemy against which spines are no 

 protection — the hunter wasp, which, as we have seen in the 

 work of Bates, sometimes provisions its nest wholly with 

 spiders of this family. Mr. Smith gives like testimony, 

 saying : 



" Spines on the abdomen of certain spiders would serve as a 

 protection against vertebrate enemies, though they do not pro- 

 tect against the hunter wasps, which frequently provision their 

 nests with these species." lie adds, however, that most of the 

 spiny spiders are common, and that their colors make them 

 conspicuous ; just as butterflies that are protected by an odor 

 are common and bright-colored.* 



♦Letter on Euemies of Si:»iders- 



