Alder Leaf Beetle

Natural Habitat

Found primarily in damp areas where alder trees grow, such as riverbanks, wetlands, and temperate forests.

Diet & Feeding

Strictly herbivorous; larvae and adults feed on the leaves of alder trees and sometimes hazel, birch, or hornbeam.

Behavior Patterns

Adults emerge from winter hibernation in spring to mate and lay eggs; they are known for their metallic blue-black appearance and slow-moving nature on foliage.

Risks & Benefits

Generally harmless to humans; while they can cause skeletonization of alder leaves, they are rarely considered a major pest and contribute to the local ecosystem as a food source for birds and spiders.

Identified on: 4/11/2026