The Mason-Wasps 



cares to interest himself in the Eumenes to 

 perceive to what extent instinct modifies the 

 diet, according to place and season. The 

 food is plentiful but lacks variety. It con- 

 sists of tiny caterpillars, by which I mean 

 the grubs of small Butterflies or Moths. 

 This is proclaimed by the structure, for we 

 observe the usual caterpillar organism in the 

 prey selected by either Wasp. The body 

 is composed of twelve segments, not inclu- 

 ding the head. The first three have true 

 legs, the next two are legless, then come 

 four segments with prolegs, two legless seg- 

 ments and, lastly, a terminal segment with 

 prolegs. It is exactly the same organization 

 which we saw in the Ammophila's Grey 

 Worm. 



My old notes give the following descrip- 

 tion of the caterpillars found in the nest of 

 E. Amadel: a pale-green or, less often, 

 yellowish body covered with short white 

 hairs; head wider than the front segment, 

 dead-black and also bristling with hairs. 

 Length: 16 to 18 millimetres; 1 width: 

 about 3 millimetres. 2 It is more than a 

 quarter of a century since I jotted down this 

 descriptive sketch; and today, at Serignan, I 



1 .63 inch to .7 inch. Translator's Note. 

 2 .12 inch. Translator's Note. 

 14 



