Boxelder Bugs (nymphs)

Natural Habitat

Found on trees, particularly boxelder trees, maple trees, and ash trees, where they feed on seeds and developing leaves. They are also commonly found on the sunny, warm sides of buildings, especially in late summer and fall, as they seek overwintering sites.

Diet & Feeding

Boxelder bugs are primarily phytophagous, feeding on the developing seeds, leaves, and flowers of boxelder trees and other maples. Nymphs, like adults, use their piercing-sucking mouthparts to extract sap. They are particularly fond of the female (seed-bearing) boxelder trees.

Behavior Patterns

Boxelder bugs exhibit aggregate behavior, especially visible in the nymph stage as shown, where they cluster together on branches, tree trunks, and around the bases of host trees. In late summer and fall, adults often congregate in large numbers on sunny walls of buildings, seeking sheltered locations to overwinter. They are known for sunning themselves in groups. They undergo gradual metamorphosis, with nymphs molting several times before reaching adulthood.

Risks & Benefits

Boxelder bugs are generally considered nuisance pests rather than destructive ones. They typically do not cause significant damage to healthy trees. However, large aggregations can be unsightly, and they may enter homes in the fall seeking warmth, where they can become a nuisance. They do not bite people or pets, nor do they transmit diseases. When crushed, they may emit a foul odor and can stain surfaces with their excretions. They have no significant benefits to the ecosystem, but they are a food source for some predatory insects and birds.

Identified on: 9/10/2025