Pest description and damage Small bees, 0.18 inch long and metallic blue or blue-green, burrow into the pith of cut stems to create cells for their young. Cells are provisioned with pollen and nectar. Damage is not serious. These bees can burrow only in pruned stems.
Biology and life history Females overwinter as adults in partially or completely excavated stems. In the spring, the female modifies this resting place (hibernaculum) into a brood nest by further excavation. When a desired depth is reached, she collects pollen and nectar, places this mixture at the base of the burrow, lays an egg on the provision, and then caps off the cell with plant material. Several cells are constructed end to end in each plant stem. The maturing bees then chew their way out of the stem.
Cover cut stems ends with wax to prevent burrowing and egg laying. Prune out and destroy or burn damaged canes in winter where females are hibernating and before they emerge in spring.