Boxelder bug vs Large milkweed bug
These two are easy to mix up. Here's how to tell a boxelder bug from a large milkweed bug, and whether either one bites or stings.
Boxelder bug
Boisea trivittata
Large milkweed bug
Oncopeltus fasciatus
≠The key differences
Milkweed bug is orange and black but has a broader orange area and different wing pattern; milkweed bugs are associated with milkweed, not boxelder.
Mostly black with thin red-orange lines on the pronotum and wing edges rather than broad orange bands; found on boxelder and maple trees and often gathers on sunny house walls in autumn.
⚖︎Side by side
| Boxelder bug | Large milkweed bug | |
|---|---|---|
| To humans | Non-toxic | Non-toxic |
| Size | 9-16 mm long | 12-18 mm body length |
| Colours | Black, Red, Orange | Orange-red, Black, White (small markings on legs/edges) |
| Family | Rhopalidae | Lygaeidae |
| Habitat | Deciduous trees (especially boxelder, maples, ash), nearby gardens, rock piles, building exteriors and sheltered overwintering sites | Open areas, meadows, roadsides, and gardens where milkweed grows; commonly on the seed pods and blossoms of milkweed plants |
| Range | Widespread across much of North America; especially common where boxelder (Acer negundo) and other maples grow | Native to the Americas: widespread in the United States and southern Canada (where adults are summer migrants in the north), through Mexico, Central America and the Caribbean into parts of South America |
| Active | Active spring through fall; most visible late summer and fall during mating and pre-overwintering aggregation; diurnal, often basking in sun | Active in spring through autumn where milkweed is present; mainly diurnal (active during the day) |
| Pest? | Yes | No |
🔍How to spot a boxelder bug
- Black, elongated body 9-16 mm long with three red or orange longitudinal stripes on the pronotum
- Red or orange young nymphs without fully developed wings; adults have red edging on the wings
- Often found on boxelder or maple trees and in sunny aggregations on warm building walls
🔍How to spot a large milkweed bug
- Bright orange-red body with bold black banding across wings and black markings on head and pronotum
- Adult length 12-18 mm, elongated oval shape with wings covering the abdomen
- Aggregates on milkweed seed pods and flowers in conspicuous groups
?Frequently asked questions
What is the difference between a boxelder bug and a large milkweed bug?
Milkweed bug is orange and black but has a broader orange area and different wing pattern; milkweed bugs are associated with milkweed, not boxelder. Mostly black with thin red-orange lines on the pronotum and wing edges rather than broad orange bands; found on boxelder and maple trees and often gathers on sunny house walls in autumn.
Is a boxelder bug or a large milkweed bug more dangerous?
Boxelder bug: Non-toxic. Large milkweed bug: Non-toxic. Boxelder bugs do not bite or sting and are not dangerous. Large milkweed bugs are not venomous and do not present a medical threat.
Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.