Landscaping pebbles attract nesting by the native ground-nesting bee Halictus rubicundus (Hymenoptera: Halictidae)

Most species of bees nest underground. Recent interest in pollinator-friendly gardens and landscaping focuses on planting suitable flowering species for bees, but we know little about providing for the ground-nesting needs of bees other than leaving them bare dirt surfaces. In this study, a surface layer of decorative flat stream pebbles was experimentally deployed in 24 paired subplots amid a nesting aggregation of the bee Halictus rubicundus. Over 2 years, females consistently preferred to nest amid the pebbles rather than adjacent bare dirt. Species of Halictus and their relatives (Lasioglossum, Dialictus) are widespread native floral generalists found in many urban areas of the northern hemisphere. Discovery of this practical soil nesting enhancement for H. rubicundus offers an aesthetically acceptable landscaping technique to promote these bees' nesting, particularly where pollinator gardens and bee-friendly landscaping is already being provided.