A Morphological Study of the Tibial Spurs of Bees of the Subfamily Halictinae (Hymenoptera: Halictidae) of Eastern North America1

Abstract

Bees of the subfamily Halictinae, commonly called sweat bees, possess two pairs of spurs on the hind tibiae, the inner pair being branched in the female. Spurs of samples of representative species of all genera of Halic-tinae occurring in Eastern North America were examined microscopically to ascertain morphological groupings of spur form. Five morphologically distinct spur forms indicative of generic groupings are recognized: Sphccodcs, Agapostcmon, Augochlora (containing Augo-chlora and Augochlorclla), Augochloropsis, and Halictus (containing Halictus s.l. and Lasioglossum s.l.). The spurs of representatives of the various subgenera in the Halictus grouping are analyzed in detail and the implications of this study in correctly determining natural sub-genera of the grouping are discussed. Spur form does not appear useful in separating species within a genus except in the genus Halictus s.l.