CONVERGENCE OF COLORATION BETWEEN AMERICAN PILOSE FLIES AND BUMBLEBEES (BOMBUS)

¹ RESEARCH FELLOW OF THE INTERNATIONAL EDUCATION BOARD, COLUMBIA UNIVERSITY, NEW YORK

1. The European Syrphid fly Volucella Bombylans and its varieties, V. hæmoroidalis and V. plumata have a coloration which corresponds to the coloration of the majority of European bumblebees. The same is true of many other pilose flies of Europe.

2. The Caucasian Volucella bombylans caucasica has a coloration which corresponds to the coloration of various bumblebees of this mountain region. The same is true for other pilose flies of this zone.

3. The American Volucella bombylans evecta-americana of the eastern states and 8 other species of Syrphid flies have exactly the same color patterns as six different Bombus species of this region; four different Bombus of the same area have the same type of coloration as three other beelike flies of the eastern states.

4. Volucella bombylans evecta sanguinea, and Eristalis flavipes var. melanostoma of the eastern states are rare and parallel variations which have analogous coloration to that of Volucella bomb. var. rufomaculata of the facialis group and of the Rocky Mountain region.

5. Volucella bombylans arctica of the evecta group is similar in coloration to the arctic bumblebee Bombus gelidus and to other species.

6. Volucella bombylans var. rufomaculata of the Rocky mountains has a similar coloration to twelve different bumblebee species which occur in the same region. The Asilid fly Dasyllis fernaldi of the same zone has a corresponding coloration to V. rufomaculata and to the twelve bumblebee species.

7. Volucella bomb. facialis of the Pacific coast has analogous color patterns to three bumblebee species of this zone. Volucella bomb. facialis lateralis of the Canadian zone and V. bomb. evecta of the eastern states have not been studied on account of absence of data as to their distribution.