1916] Johnson — The Volucella hombylans Group in America 161 



parasitic on the living larvae or pupae, so that the association is 

 friendly and consequently not resented by the more powerful 

 Hy menoptera ; beyond this the scavengers have probably gradually 

 mimicked their hosts in order to obtain the protection afforded 

 by their aculeate powers. Dr. Sharp's observations on the larvae 

 of V. inanis, which live in the nests of Vespa crabro, tend to show 

 that the larvae are welcome scavengers who \We on the pupae 

 which have recently died and who thereby prevent those dead 

 pupae from contaminating the nest, for which friendly action their 

 imitative coloring may possibly indicate them as friends rather 

 than conceal them as enemies." 



Twenty-one specific names are placed in the synonomy by 

 Verrall and twenty-four (including the American V. evecta, 

 sanguinea and facialis) are in the synonomy under V. bombylans 

 in the Katalog der paliiarktischen Dipteren, 1907. 



•I have before me seventeen specimens of the European and 

 Asiatic forms and forty-one specimens of the American forms. 

 Specimens from Knight Valley, Cal. (H. Edwards), described as 

 fascialis Will, cannot be separated satisfactorily from the Euro- 

 pean forms, plumata and hcemorrhoidalis. The pile on the pleura is 

 black and the face and front yellow. A male from Alai Mountains, 

 Turkestan, shows the same variation as a specimen from Califor- 

 nia, the lateral stripe of yellow pile being absent in front of the 

 tran verse suture; the face, however, is black and the antennae 

 slightly darker in the Asiatic specimen. The color of the antennae 

 used by Bigot in his table (Ann. Soc. Ent., France, July, 1883, 

 p. 79) seems to be of little value in separating the forms as there 

 are apparently all gradations from reddish brown to brownish 

 black. As the typical bombylans is not known in America it is 

 perhaps best at present to use fascialis for the American form and 

 treat all the American forms as independent of the European. 



There is a form closely resembling fascialis, with the dorsum of 

 the thorax black pilose and face yellow, but the pile on the pleura is 

 yellow. It seems to be confined to the northeastern United 

 States and Canada. Before me are specimens from Franconia, 

 N. H. (Mrs. A. T. Slosson), Wales, Me., June 20, 1909, and Lake 

 Aziscoos, Me., July 8, 1916 (C. A. Frost), Red Indian Lake, 

 Newfoundland, July 20, 1906 (Owen Bryant), and Lewisport, 

 Newfoundland, July (L. P. Gratacap). To this form I assign 



