Boxelder bug
The boxelder bug is a true bug in the genus Boisea, best known as a nuisance insect around homes and buildings.
The boxelder bug (Boisea trivittata) is a true bug best known as a nuisance insect around homes and buildings. It feeds mainly on boxelder trees and other maples, and sometimes on ash and certain fruit trees. The insects are usually not considered serious plant pests, but large aggregations can be troublesome indoors.
Description
Adult boxelder bugs are flattened, elongated true bugs about 1/2 inch (12–15 mm) long. They have dark brownish-black bodies with red or orange markings, including three red stripes on the thorax and red lines on the wings and body margins.
Distribution and habitat
Boxelder bugs are native to much of North America, including Canada, where they occur wherever boxelder trees and related maples grow. They are often seen on trunks, rocks, and buildings exposed to sunlight, especially in late summer and autumn.
Life cycle and behaviour
Boxelder bugs feed and reproduce on host trees during warm months. In autumn, adults often gather on sunny south- and west-facing walls as they seek overwintering sites. They overwinter as adults, and sometimes nymphs, in protected dry places such as wall voids, attics, and cracks.
Human interactions
Boxelder bugs are considered a nuisance because large numbers may enter homes, but they are not known to cause structural damage or significant damage to plants. They are not known to sting or transmit disease and are generally not known to bite, though rare defensive biting has been reported. They may stain light surfaces with droppings, and handling or crushing them can produce an unpleasant smell.
Key facts
- Boxelder bugs feed mainly on sap from boxelder trees, especially female or seed-bearing trees.
- They are generally considered nuisance pests rather than major plant pests.
- Adults often gather on sunny south- and west-facing walls in autumn as they seek overwintering sites.
- They do not usually damage buildings, but their droppings can stain surfaces and crushed insects can release an unpleasant odor.
- The species is native to much of North America and occurs where boxelder trees grow.
Boxelder bugs are found in Canada wherever boxelder trees and related maples occur, and they are a familiar nuisance insect in Canadian homes and landscapes.
Frequently asked questions
What is a boxelder bug?
Are boxelder bugs harmful to people?
Do boxelder bugs damage houses?
What do boxelder bugs eat?
Why do boxelder bugs come into houses?
References
- UNH Extension — Supports: Feeding habits, host plants, nuisance status, and physical description.
- UMN Extension — Supports: Overwintering behaviour, nuisance status, and attraction to buildings.
- USDA Forest Service — Supports: North American distribution, host association, and limited plant damage.
- NPIC — Supports: Nuisance nature, staining, odor when crushed, and lack of disease transmission.
- Cornell Cooperative Extension Ontario — Supports: Canadian relevance, overwintering behaviour, and host plant association.