Some of the most deadly foes of Spiders are the Solitary Wasps. There are many species of _Pompilus_ (vol. vi. p. 101), which, having excavated holes in clay banks, store them with spiders or other creatures which they have paralysed by their sting. They then deposit an egg in the hole, and immediately seal up the orifice. This habit is found to characterise the solitary wasps of all parts of the world. Belt[291] relates the capture of a large Australian spider by a wasp. While dragging its victim along, it was much annoyed by the persistent presence of two minute flies, which it repeatedly left its prey to attempt to drive away. When the burrow was reached and the spider dragged into it, the two flies took up a position on either side of the entrance, doubtless with the intention of descending and laying their own eggs as soon as the wasp went away in search of a new victim. Fabre[292] gives an interesting account of one of the largest European Pompilidae, _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 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 egg-nest with a single spider, while others collect many for the purpose.