Is it the colouring? Not at all. There is no lack of instances. What a variety of hues and metallic reflections, distributed in a host of different fashions, appear in the Buprestes that are hunted by the Cerceris celebrated by Leon Dufour. (Jean Marie Leon Dufour (1780-1865) was an army surgeon who served with distinction in several campaigns and subsequently practised as a doctor in the Landes. He attained great eminence as a naturalist. Cf. "The Hunting Wasps": chapter 1; also "The Life of the Spider": chapter 1.--Translator's Note.) A painter's palette, containing crushed gold, bronze, ruby and amethyst, would find it difficult to rival these sumptuous colours. Nevertheless the Cerceris makes no mistake: all this nation of insects, so indifferently attired, represents to her, as to the entomologist, the nation of the Buprestes. The inventory of the Hornet's larder will include Diptera clad in grey or russet frieze; others are girdled with yellow, flecked with white, adorned with crimson lines; others are steel-blue, ebony black, or coppery green; and underneath this variety of dissimilar costumes we find the invariable Fly. Let us take a concrete example. Ferrero's Cerceris (C. Ferreri, VAN DER LIND) consumes Weevils. Her burrows are usually lined with Phynotomi and Sitones both an indeterminate grey, and Otiorhynchi, black or tan-coloured. Now I have sometimes happened to unearth from her cells a collection of veritable jewels which, thanks to their bright metallic lustre, made a most striking contrast with the sombre Otiorhynchus. These were the Rhynchites (R. betuleti), who roll the vine-leaves into cigars. Equally magnificent, some of them were azure blue, others copper gilt, for the cigar-roller has a twofold colouring. How did the Cerceris manage to recognize in these jewels the Weevil, the near relative of the vulgar Phynotomus? Any such encounters probably found her lacking in expert knowledge; her race cannot have handed down to her other than very indeterminate propensities, for she does not appear to make frequent use of the Rhynchites, as is proved by my infrequent discovery of them amid the mass of my numerous excavations. For the first time, perhaps, passing through a vineyard, she saw the rich Beetle gleaming on a leaf; it was not for her a dish in current consumption, consecrated by the ancient usages of the family. It was something novel, exceptional, extraordinary. Well, this extraordinary creature is recognized with certainty as a Weevil and stored away as such. The glittering cuirass of the Rhynchites goes to take its place beside the grey cloak of the Phynotomus. No, it is not the colour that guides the choice.