**Maple Leafcutting Bees** (*Megachile* species, sometimes referring to a specific species specializing in maples) are part of a family of **solitary bees** that do not form perennial colonies or pose a stinging hazard to humans. They are beneficial pollinators, but they cause minor, noticeable **aesthetic damage** to plants, primarily maples, roses, ash, and lilac. The conflict arises because the female bees cut perfectly semicircular or circular pieces of leaf material, which she uses to line and seal the cells of her nest, leaving behind distinctive “cutout” damage on the foliage.
Taxonomy and Classification
Leafcutting Bees belong to the order Hymenoptera, family Megachilidae. They undergo complete metamorphosis. They are solitary, meaning each female builds and provisions her own nest, typically in pre-existing cavities (hollow stems, nail holes, insect tunnels). They are excellent pollinators, carrying pollen on the underside of their abdomen (the scopa) rather than their legs.
Physical Description
Adult Leafcutting Bees are robust, dark bees, 1/4 to 3/4 inch long.
- **Appearance (Key ID):** Often dark brown or black, with light bands of hair on the abdomen. They collect pollen on the underside of their abdomen, giving the underside a distinct yellow/orange coloration.
- **Damage Sign (Key ID):** **Perfectly smooth, circular, or semicircular cutouts** in the edges or centers of leaves, most noticeable on plants like roses and maples. The damage looks aesthetically poor but is rarely harmful to the plant’s overall health.
- **Conflict:** Minor aesthetic damage; negligible stinging hazard.
Distribution and Habitat
Leafcutting Bees are found globally. Their habitat includes gardens, orchards, and forested areas. They nest in cavities in wood, hollow plant stems, or “bee hotels” (man-made nesting structures).
Behavior and Conflict
The conflict is low and purely aesthetic, balanced by their beneficial role.
- **Leaf Cutting:** The female is simply using the material to construct a secure, moist environment for her offspring. She does not eat the leaf material.
- **Pollination (Beneficial):** They are highly valuable, native pollinators, particularly important for some commercial crops like alfalfa.
- **Stinging:** They are non-aggressive and will only sting if severely provoked or accidentally squeezed; their sting is milder than a honey bee’s.
Management and Prevention
Control is generally unwarranted and discouraged due to their beneficial nature.
- The damage is cosmetic; the plant will continue to photosynthesize and grow normally. Tolerance is the best approach.
- If damage is intolerable on high-value ornamental plants, netting or row covers can be used for temporary protection during their peak activity (mid-summer).
- **Strongly discouraged.** Applying insecticides will kill this valuable pollinator and will not prevent a new bee from making her cuts the next day.
Conservation and Research
Leafcutting Bees are conserved as vital native pollinators. Research focuses on their effectiveness in pollinating specific crops (especially alfalfa) and improving the design of man-made nesting structures to support their populations.