The search is concluded; the acorn is recognised as unoccupied.  The drill is applied to the surface and rotated for hours; then, very often, the insect departs, disdaining the result of her work.  Why such protracted efforts?  Was the beetle piercing the fruit merely to obtain drink and refreshment?  Was the beak thrust into the depths of the base merely to obtain, from the choicer parts, a few sips of nutritious sap?  Was the whole undertaking merely a matter of personal nourishment?

At first I believed this to be the solution, though surprised at the display of so much perseverance rewarded by the merest sip.  The behaviour of the males, however, forced me to abandon this idea.  They also possess the long beak, and could readily make such perforations if they wished; yet I have never seen one take up his stand upon an acorn and work at it with his augur.  Then why this fruitless labour?  A mere nothing suffices these abstemious creatures.  A superficial operation performed upon the surface of a tender leaf yields them sufficient sustenance.

If the males, the unoccupied males who have leisure to enjoy the pleasures of the palate, ask no more than the sap of the leaf, how should the mothers, busied with the affairs of the breeding-season, find time to waste upon such dearly bought pleasures as the inner juices of the acorn?  No, the acorn is not perforated for the purpose of drinking its juices.  It is possible that once the beak is deeply sunk, the female may take a mouthful or two, but it is certain that food and drink are not the objects in view.

At last I begin to foresee the solution of the problem.  The egg, as I have said, is always at the base of the acorn, in the midst of a soft cottony layer which is moistened by the sap which oozes from the stalk.  The grub, upon hatching out, being as yet incapable of attacking the firm substance of the cotyledons, masticates the delicate felt-like layer at the base of the cup and is nourished by its juices.

But as the acorn matures this layer becomes more solid in its consistency.  The soft tissues harden; the moist tissues dry up.  There is a period during which the acorn fulfils to perfection the conditions most conducive to the welfare of the grub.  At an earlier period matters would not have reached the desired stage; at a later period the acorn would be too mature.

The exterior of the acorn gives no indication whatever of the progress of this internal cookery.  In order not to inflict unsuitable food on the grub, the mother beetle, not sufficiently informed by the look of the acorn, is thus obliged to taste, at the end of her trunk, the tissues at the base of the cup.