Abstract
Two species of Apidae occur on Ellesmere Island: Megabombus (Megabombus) polaris (Curtis) and M. (M.) hyperboreus (Schönherr). Some observations on their activity are presented. Three nests built on the surface of the ground are described. The colonies were of small size. Nest No. 1 contained only polaris; Nests Nos. 2 and 3 contained polaris workers and hyperboreus sexuals, as adults or brood. Usurpation is suggested to explain the workerless condition of hyperboreus in Nests Nos. 2 and 3.

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