Boxelder Bug
Boisea trivittata
Anatomy
Identification
Distinguishing Features
- Flattened, elongated oval body shape
- Bright red/orange markings on black background
- Three red stripes on the thorax (pronotum)
- Red wing margins forming X-pattern when wings closed
- Nymphs are smaller, rounder, and entirely bright red
Biology
Lifecycle
Overwinter as adults in sheltered locations. Emerge in spring to feed on fallen maple seeds and mate. Two generations per year; the second generation aggregates in fall seeking overwintering sites.
Diet
Feed primarily on seeds, flowers, and leaves of Manitoba Maple (Acer negundo/Boxelder), Silver Maple, and Ash trees. Use piercing-sucking mouthparts but do not cause significant damage to trees.
Nesting
Do not nest or breed indoors. In fall, they aggregate on warm, sun-facing building surfaces (south and west walls) before seeking cracks and crevices to overwinter. Attracted by solar heating of structures.
Signs of Infestation
Mass aggregations on walls
Hundreds or thousands of bugs clustering on sunny exterior walls, especially south and west-facing, in September and October.
Bugs entering through gaps
Boxelder bugs streaming into homes through cracks around windows, doors, siding, and utility entries in fall.
Indoor sightings in winter
Finding active bugs indoors on warm, sunny winter days when they emerge from wall voids seeking warmth.
Red stains on surfaces
Crushed bugs leave reddish-brown stains on curtains, walls, and upholstery. Their fecal matter also stains.
Foul odour when disturbed
When crushed or handled, boxelder bugs emit a pungent, unpleasant smell.
Where They Nest
- South and west-facing exterior walls
- Around window and door frames
- In wall voids and behind siding
- Near host trees (Manitoba Maple, Silver Maple, Ash)
- On sun-warmed decks and patios
Distribution in Canada
Common throughout southern Canada wherever host trees (Manitoba Maple, Silver Maple, Ash) are present. Populations fluctuate cyclically - some years see massive outbreaks.
Active Season
Most visible in September-October when aggregating on buildings. Adults may emerge on warm winter days. Spring emergence occurs in April-May.
Prevention
- Seal cracks around windows, doors, and siding before fall
- Repair damaged screens and install door sweeps
- Consider removing female (seed-bearing) Boxelder trees near the home
- Apply exterior perimeter treatment in September before aggregation
- Vacuum indoor bugs rather than crushing (prevents staining)
Professional Treatment
Exterior perimeter treatment in late August or September creates a barrier before bugs aggregate and seek entry. For existing indoor populations, targeted treatment of entry points and harborage areas provides control. Host tree management may be recommended for severe cases.
Get General Pest Control ServiceFrequently Asked Questions
What does a Boxelder Bug eat?
Feed primarily on seeds, flowers, and leaves of Manitoba Maple (Acer negundo/Boxelder), Silver Maple, and Ash trees. Use piercing-sucking mouthparts but do not cause significant damage to trees.
Where does a Boxelder Bug nest?
Do not nest or breed indoors. In fall, they aggregate on warm, sun-facing building surfaces (south and west walls) before seeking cracks and crevices to overwinter. Attracted by solar heating of structures.
When is a Boxelder Bug most active?
Most visible in September-October when aggregating on buildings. Adults may emerge on warm winter days. Spring emergence occurs in April-May.
What are the signs of a Boxelder Bug infestation?
Mass aggregations on walls: Hundreds or thousands of bugs clustering on sunny exterior walls, especially south and west-facing, in September and October. Bugs entering through gaps: Boxelder bugs streaming into homes through cracks around windows, doors, siding, and utility entries in fall. Indoor sightings in winter: Finding active bugs indoors on warm, sunny winter days when they emerge from wall voids seeking warmth. Red stains on surfaces: Crushed bugs leave reddish-brown stains on curtains, walls, and upholstery. Their fecal matter also stains. Foul odour when disturbed: When crushed or handled, boxelder bugs emit a pungent, unpleasant smell.
How can I prevent a Boxelder Bug infestation?
Seal cracks around windows, doors, and siding before fall. Repair damaged screens and install door sweeps. Consider removing female (seed-bearing) Boxelder trees near the home. Apply exterior perimeter treatment in September before aggregation. Vacuum indoor bugs rather than crushing (prevents staining).
How is a Boxelder Bug treated?
Exterior perimeter treatment in late August or September creates a barrier before bugs aggregate and seek entry. For existing indoor populations, targeted treatment of entry points and harborage areas provides control. Host tree management may be recommended for severe cases.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Arthropoda
- Class
- Insecta
- Order
- Hemiptera
- Family
- Rhopalidae
- Genus
- Boisea
