Some Solitary ^Yasps of Texas. 71 



the larva is at least half-grown. Another instance, showing a still 

 greater step in the direction indicated, is shown by an AmniopJiila 

 urnana described by the Peckhams. This species lays the &g^ on 

 the first caterpillar brought in and stores the other or others as soon 

 as she can. In one case, the mother wasp on her return with the 

 second caterpillar found a larva a day old feasting on the caterpillar 

 already provided. 



It is interesting to note that, parallel with the working out of 

 the instinct to store the nest quickly and close it up over the un- 

 hatched egg, runs the development of the stinging instinct, which 

 aims to paralyze the prey to preserve it for the future offspring. 

 Thus Microbemhe.v, which is the most generalized in the mode of 

 procuring food, seldom needs to sting her prey, for she nearly al- 

 ways finds it dead. When she stings, it is to kill and from a single 

 observation I judge her to be very awkward in the application of 

 her sting. The five caterpillars I saw her carry into her nest were 

 all dead. The greater part of the caterpillars captured by Ammo- 

 phila or Odynerus, wasps that specialize in that kind of prey, are 

 brought into the nest merely paralyzed instead- of killed outright. 



B ember tex and other fly-catchers sting their flies to death with 

 a single prolonged sting as I observed in Chap, IV. This suggests 

 the idea that the primary purpose of the sting is to overcome the 

 victim. 



Among most of the other solitary wasps the tendency to merely 

 paralyze the victim is more or less perfectly developed. Bugs, 

 grass-hoppers, bees, spiders or caterpillars are sometimes brought in 

 stung to death, but often they live from a few days to many. The 

 nearest approach to perfection is reached in the Ammophilae. So 

 nearly perfect is the habit here that Fabre was led to assert that 

 two conditions always obtain with Ammophila's caterpillars and are 

 absolutely essential to the perpetuity of the species: first, that the 

 caterpillar must be sufTiciently paralyzed to insure the safety of the 

 egg, yet secondly, it must remain alive sufficiently long to furnish 

 fresh food for the growing larva. Though Fabre has noted a 

 slight variation in the number and order of the stings administered 

 he insists of the necessity of stinging the caterpillar in the middle 

 segments, one of which is to receive the egg, and his observation^ 

 seem to bear him out. In Chap. II, I have given my own observa- 

 tions on five caterpillars of Ammophila procera which fulfilled to a 

 nicety the condition thus laid down by Fabre. In each case the 



