This paper describes the results of studies on the wild bees of Nova Scotia, which were carried out in connection with apple pollination investigations in the Annapolis-Cornwallis Valley, Nova Scotia.The biology of the Apoidea in general is reviewed from the literature, and a list of bees taken on apple bloom is given. As the members of the genera Halictus and Andrena were found to be the most important native pollinators, the greater part of the paper is devoted to accounts of the habits and life histories of representative species.The members of the genus Andrena were found to have a simple type, such as is generally found among solitary bees. The females provision the nest and then die; the larvae develop to the pupal stage in their underground cells, then emerge as adults the following season. All Nova Scotian species studied were one-generation forms.The bees of the genus Halictus show a primitive social organization, more complex in some species than in others. The first brood consists of females only, which are apparently sterile and work at nest construction, the gathering of pollen, etc. They are followed later in the season by a brood of males and females; these females, after being fertilized, hibernate for the winter, while the males die in the fall. The hibernating habits of different species are described, and notes are given on some parasites and inquilines of the two genera.