Considered in respect of quality, the food has just disclosed our profound ignorance of the origins of instinct. Success falls to the blusterers, to the imperturbable dogmatists, from whom anything is accepted if only they make a little noise. Let us discard this bad habit and admit that really, if we go to the bottom of things, we know nothing about anything.
Scientifically speaking, nature is a riddle to which human curiosity finds no definite solution. Hypothesis follows hypothesis; the theoretical rubbish-heap grows bigger and bigger; and still truth escapes us. To know how to know nothing might well be the last word of wisdom.
Considered in respect of quantity, the food sets us other problems, no less obscure. Those of us who devote ourselves assiduously to studying the customs of the game-hunting Wasps soon find our attention arrested by a very remarkable fact, at the time when our mind, refusing to be satisfied with sweeping generalities, which our indolence too readily makes shift with, seeks to enter as far as possible into the secret of the details, so curious and sometimes so important, as and when they become better-known to us. This fact, which has preoccupied me for many a long year, is the variable quantity of the provisions packed into the burrow as food for the larva.
Each species is scrupulously faithful to the diet of its ancestors. For more than a quarter of a century I have been exploring my district; and Ihave never known the diet to vary. To-day, as thirty years ago, each huntress must have the game which I first saw her pursuing. But, though the nature of the victuals is constant, the quantity is not so. In this respect the difference is so great that he would need to be a very superficial observer who should fail to perceive it on his first examination of the burrows. In the beginning, this difference, involving two, three, four times the quantity and more, perplexed me extremely and led me to the conclusions which I reject to-day.
Here, among the instances most familiar to me, are some examples of these variations in the number of victims provided for the larva, victims, of course, very nearly identical in size. In the larder of the Yellow-winged Sphex, after the victualling is completed and the house shut up, two or three Crickets are sometimes found and sometimes four. Stizus ruficornis (Cf. "The Hunting Wasps": chapter 20; also "Bramble-bees and Others":
chapter 9.--Translator's Note.), established in some vein of soft sandstone, places three Praying Mantes in one cell and five in another. Of the caskets fashioned by Amedeus' Eumenes (Cf." The Mason-wasps": chapter 1.--Translator's Note.) out of clay and bits of stone, the more richly endowed contain ten small caterpillars, the more poorly furnished five. The Sand Cerceris (Cf. "The Hunting Wasps": chapter 2.--Translator's Note.)will sometimes provide a ration of eight Weevils and sometimes one of twelve or even more. My notes abound in abstracts of this kind. It is unnecessary for the purpose in hand to quote them all. It will serve our object better if I give the detailed inventory of the Bee-eating Philanthus and of the Mantis-hunting Tachytes, considered especially with regard to the quantity of the victuals.
The slayer of Hive-bees is frequently in my neighbourhood; and I can obtain from her with the least trouble the greatest number of data. In September Isee the bold filibuster flying from clump to clump of the pink heather pillaged by the Bee. The bandit suddenly arrives, hovers, makes her choice and swoops down. The trick is done: the poor worker, with her tongue lolling from her mouth in the death-struggle, is carried through the air to the underground den, which is often a very long way from the spot of the capture. The trickling of earthy refuse, on the bare banks, or on the slopes of footpaths, instantly reveals the dwellings of the ravisher; and, as the Philanthus always works in fairly populous colonies, I am able, by noting the position of the communities, to make sure of fruitful excavations during the forced inactivity of winter.
The sapping is a laborious task, for the galleries run to a great depth.
Favier wields the pick and spade; I break the clods which he brings down and open the cells, whose contents--cocoons and remnants of provisions--Iat once pour into a little screw of paper. Sometimes, when the larva is not developed, the stack of Bees is intact; more often the victuals have been consumed; but it is always possible to tell the number of items provided.
The heads, abdomens and thoraxes, emptied of their fleshy substance and reduced to the tough outer skin, are easily counted. If the larva has chewed these overmuch, the wings at least are left; these are sapless organs which the Philanthus absolutely scorns. They are likewise spared by moisture, putrefaction and time, so much so that it is no more difficult to take an inventory of a cell several years old than one of a recent cell.
The essential thing is not to overlook any of these tiny relics while placing them in the paper bag, amid the thousand incidents of the excavation. The rest of the work will be done in the study, with the aid of the lens, taking the remains heap by heap; the wings will be separated from the surrounding refuse and counted in sets of four. The result will give the amount of the provisions. I do not recommend this task to any one who is not endowed with a good stock of patience, nor above all to any one who does not start with the conviction that results of great interest are compatible with very modest means.
My inspection covers a total of one hundred and thirty-six cells, which are divided as in the table below:
2 cells each containing 1 Bee 52 cells each containing 2 Bees 36 cells each containing 3 Bees 36 cells each containing 4 Bees 9 cells each containing 5 Bees 1 cell containing 6 Bees ---136
