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Our fashionable theorists have availed themselves of this brown and yellow to cite the Volucella as a striking instance of protective mimicry. Obliged, if not on her own behalf, at least on that of her family, to introduce herself as a parasite into the wasp's home, she resorts, they tell us, to trickery and craftily dons her victim's livery.

In vain I prolong my examination: there is no fluster of any kind. The Volucella grub is treated as a friend, or at least as a visitor that does not matter. There is no attempt to dislodge it, to worry it, to put it to flight. Nor does the grub seem to trouble greatly about those who come and go. Its tranquillity, tells us that it feels at home.

I have been experimenting all along with big Volucella grubs, colored with the dirty red which comes with age. What effect will pure white produce? I sprinkle on the surface of the combs some larvae that have lately left the egg. The tiny, snow-white grubs make for the nearest cells, go down into them, come out again and hunt elsewhere.

And a suspicion comes to one's mind: can it be that the Volucella and the rest are not what the accepted theories of natural history call them, namely, enemies, grub killers sacking the wasps' nest? We will look into this by examining them when they are hatched. Nothing is easier, in September and October, than to collect the Volucella's eggs in such numbers as we please.

Obliged, if not for its own sake at least for that of its family, to force itself into the wasp's dwelling as a parasite, it deceitfully dresses itself, we are told, in the livery of its victim, thus affording the most curious and striking example of mimicry; and naturalists insufficiently informed would regard it as one of the greatest triumphs of evolution. Now what does the Volucella do?

What it wants down there, at the bottom of the cells, behind the grubs, cannot be decided by direct observation; it must be guessed at. Since the visited larva remains intact, it is not prey that the Volucella grub is after. Besides, if murder formed part of its plans, why descend to the bottom of the cell, instead of attacking the defenseless recluse straight way?

Were it an enemy or merely an intruder, it would be exterminated; as a deserving assistant, it is respected. Then what need is there for the Volucella to disguise herself as a wasp? Any fly, whether clad in drab or motley, is admitted to the burrow directly she makes herself useful to the community.

Inside the wasps' nest, robust grubs are the rule and weaklings the rare exception, because of the assiduous supervision which eliminates anything that is diseased and like to die. Here, nevertheless, Volucella grubs are found, on the combs, among the busy wasps. They are not, it is true, so numerous as in the charnel house below, but still pretty frequent.

Over and over again, I bring wasp grubs and Volucella grubs together in small test tubes, which are easy to observe. The first are well and strong; I have just taken them from their cells. The others are in various stages, from that of the snowflake born the same day to that of the sturdy porcupine. There is nothing tragic about the encounter.

The wasps make no mistake: they extirpate the Saperda grub, kill it, fling it on the dust heap; they leave the Volucella grub in peace. The two strangers are quite well recognized in the secrecy of the cells: one is the intruder that must be turned out; the other is the regular visitor that must be respected.