xiv ENEMIES OF SPIDERS 369 



Calicurgus annulatus, which he observed dragging a " Tarentula " 

 to a hole in a wall. Having with great difficulty introduced its 

 burden into the cavity, the wasp deposited an egg, sealed up the 

 orifice, and flew away. Fabre opened the cell and removed the 

 spider, which, though completely paralysed, lived for seven 

 weeks. 



The same indefatigable observer describes the method adopted 

 by the comparatively small Pompilus apicalis in attacking the 

 formidable Wall-spider, Segestria perftda. The combatants are 

 well matched, and the issue of the battle would be doubtful if 

 the wasp did not have recourse to stratagem. Its whole energies 

 are directed towards forcing the spider away from its web. At 

 home, it is confident and dangerous ; when once dislodged, it 

 appears bewildered and demoralised. The wasp darts suddenly 

 towards the spider and seizes it by a leg, with a rapid effort to 

 jerk it forth, releasing its hold before the enemy has had time to 

 retaliate. The spider, however, as well as being anchored by 

 a thread from its spinnerets, is clinging to its web with its 

 hind legs, and if the jerk is not sufficiently energetic, it hastily 

 scrambles back and resumes its defensive position. Before 

 renewing the attack the wasp gives the spider time to recover 

 from the excitement of the first onset, seeking, meanwhile, the 

 retreats of other victims. Returning, it succeeds, by a more 

 skilful effort, in drawing the spider from its retreat and hurling 

 it to the ground, where, terrified and helpless, it falls an easy 

 prey. Should the insect bungle in its first attack and become 

 entangled in the web, it would itself become the victim. Certain 

 wasps thus appear to seek out particular species of spiders as 

 food for their larvae. Others are less discriminate in their 

 tastes. Again, some, as in the cases cited above, store their 

 egg-nest with a single spider, while others collect many for the 

 purpose. 



The American " blue digger wasp " (Chlorion caeruleum) 

 excavates its nest in the ground, and inserts a single large spider 

 of any species. 1 Another wasp, of the genus Elis, selects the Wolf- 

 spiders, and especially Lycosa tigrina, for the use of its larvae, 

 while Priocnemus pomilius shows a preference for the Crab- 

 spiders, or Thomisidae. 



One of the most remarkable instances is that of Pepsis 



1 M'Cook, i.e. p. 384. 

 VOL. IV 2 B 



