62 WASP STUDIES AFIELD 



Thomisid * * *, the spider was so small that she held it in 

 her mandibles well above the ground, and we speak of her 

 as dragging it only because she walked backward and acted 

 as though she were obliged to exert herself. Quite often 

 the spiders taken by this species are too large to be carried 

 and then it is necessary to drag them; this habit is so in- 

 grained that when it would be much more convenient to go 

 straight ahead, they stick to the ancient custom, and seem 

 unable to move in any other way." On another occasion 

 they found that she seized the spider by one leg and dragged 

 it off, and again : "We have twice seen a marginatus pick 

 up her spider and fly with it backward for a long distance, 

 as much as four or five feet." 



When we see the constancy of some wasps in the way of 

 carrying their prey, such as Pnononyx atratum, P. thomae, 

 Bewibix nubilipennis, Ammophila pictipennis, Odyneris dor- 

 sale and others, each of which species transports its prey 

 unvaryingly according to the fixed ways of the species, and 

 then we see the variety of methods of P. marginatus, one 

 can only wonder if natural selection will some day eliminate 

 the less favorable methods. 



The spider figuring in the above incident was taken home. 

 When examined the next day it appeared entirely unaffected 

 by the sting, but jumped up and walked away. Its abdomen 

 had been bitten into and the juices removed, so it was not 

 at all surprising when, on the third day, the spider was 

 dead. Thus it would appear that marginatus sometimes 

 indulges in animal food, although Robertson finds that it 

 frequents the flowers of Solidago nemoralis. We have 

 often noted that the prey of the Pompiloides exhibit a good 

 deal of energy and activity, after they recover from the first 

 shock of the sting, and soon afterwards succumb suddenly. 

 Hartman finds that the spider is stung to death, while the 

 Peckhams record that the spider of this wasp, which they 



