Leafcutter Bees in Mortar: Identification and Management

If you've noticed pencil-sized circular holes in your brick mortar plugged with green leaf fragments, you're likely hosting leafcutter bees. These solitary, non-aggressive pollinators don't bore into wood like carpenter bees; instead, they utilize existing cavities—such as old nail holes, gaps in mortar, or hollow stems—to build their nests. Each female provisions a cell with a pollen-nectar mixture, lays an egg, and seals it with precisely cut leaf pieces.

Why They're Beneficial

Leafcutter bees are exceptional pollinators, especially for alfalfa, blueberries, and various orchard crops. In commercial agriculture, farmers provide drilled wooden blocks to attract them. With honeybee populations declining due to mites and other stressors, native solitary bees like leafcutters, orchard mason bees, and blueberry bees are increasingly vital for local fruit production.

Should You Be Concerned?

Structural damage is minimal. The holes are pre-existing; the bees simply repurpose them. They don't sting unless handled roughly, and their activity peaks in late spring to early summer. If the holes are in a high-traffic area or you simply prefer not to host them, filling the openings with caulk after the bees have emerged (late summer) is a simple solution. Otherwise, consider leaving them be—they're doing your garden a favor.

Quick Facts

• Nesting material: Circular leaf pieces (rose, azalea, redbud leaves are favorites)
• Active season: April–July in the Southeast
• Lookalike: Mason bees use mud, not leaves, to seal nests