XIV ENEMIES OF SPIDERS 369 
Calicurgus unnulatus, 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 1 attacking the 
formidable Wall-spider, Segestria perfida. 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 
ego-nest with a single spider, while others collect many for the 
purpose. 
The American “blue digger wasp” (Chlorion caerulewm) 
excavates its nest in the ground, and inserts a single large spider 
of any species." Another wasp, of the genus £lis, selects the Wolf- 
spiders, and especially Zycosa tigrina, for the use of its larvae, 
while Pricenemus pomilius shows a preference for the Crab- 
spiders, or Thomisidae. 
One of the most remarkable instances is that of Pepsis 
1 M‘Cook, ¢t.c. p. 384. 
VOL. IV 2B 
