The Alleged “Aggressive Mimicry” of Volucellæ

Abstract

IN the course of a review (NATURE, October 6, 1892, p. 535) of a book, “Animal Coloration,” by Mr. Beddard, Mr. Poulton takes occasion to refer to a theory professing to elucidate the resemblance of Volucellæ to humble bees, &c. This reference is occasioned by the suggestion of a counter-hypothesis by Mr. Beddard. The view adopted by Mr. Poulton (“Colours of Animals,” 1890, p. 267) is that proposed by Kirby and Spence, and subsequently alluded to by Künckel d'Herculais (“Organ, et Dével. des Volucelles,” Paris, 1875) and others; but as Mr. Poulton makes no reference to these authorities he may be assumed to accept the full responsibility. In the place named he says:—“The boldness of these enemies sometimes depends on the perfection of their disguise. Thus the larvæ of flies of the genus Volucella live upon the larvæ of bees and wasps. Volucella bombylans occurs in two varieties, which prey upon the humble-bees Bombus muscorum and B. lapidarius, and are respectively like these Hymenoptera. The resemblance is very perfect, and the flies enter the nests to lay their eggs.” Mr. Beddard (l. c., p. 225) criticizes the view that the fly resembles the bee that it may with impunity enter the nest, and proposes to look on the presence of the fly's larvæ in the bees' nests as akin to the presence of supposed “pets” in the nests of ants. As Poulton points out, this suggestion leaves the original difficulty of the likeness of the fly to the bee untouched.