h I mean the grubs of small Butterflies. 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. Time and distance have not altered
the nature of the provisions.

The number of morsels served for the meal of each larva interests us
more than the quality. In the cells of Eumenes Amedei, I find sometimes
five caterpillars and sometimes ten, which means a difference of a
hundred per cent in the quantity of the food, for the morsels are of
exactly the same size in both cases. Why this unequal supply, which
gives a double portion to one larva and a single portion to another?
The diners have the same appetite: what one nurseling demands a second
must demand, unless we have here a different menu, according to the
sexes. In the perfect stage the males are smaller than the females, are
hardly half as much in weight or volume. The amount of victuals,
therefore, required to bring them to their final development may be
reduced by one-half. In that case, the well-stocked cells belong to
females; the others, more meagrely supplied, belong to males.

But the egg is laid when the provisions are stored; and this egg has a
determined sex, though the most minute examination is not able to
discover the differences which will decide the hatching of a female or
a male. We are therefore needs driven to this strange conclusion: the
mother knows beforehand the sex of the egg which she is about to lay;
and this knowledge allows her to fill the larder according to the
appetite of the future grub. What a s