We learn this from the structure, for we observe in the prey selected by either Hymenopteran the usual caterpillar organism.

The body is composed of twelve segments, not including the head.

The first three have true legs, the next two are legless, then come two segments with prolegs, two legless segments and, lastly, a terminal segment with prolegs.

It is exactly the same structure which we saw in the Ammophila's Grey Worm.
My old notes give the following description of the caterpillars found in the nest of Eumenes Amedei: "a pale green or, less often, a 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 (.63 to .7 inch .-- Translator's Note.); width: about 3 millimetres." (.12 inch .-- Translator's Note.) A quarter of a century and more has elapsed since I jotted down this descriptive sketch; and to-day, at Serignan, I find in the Eumenes' larder the same game which I noticed long ago at Carpentras.