If you’ve ever had hundreds of box elder bugs swarming your sunny exterior walls, you’ve probably asked: Are these things dangerous? It’s time to set the record straight.
In short: Box elder bugs are overwhelmingly a nuisance pest rather than a harmful one. They pose virtually no threat to people, pets, or property in Southern Ontario.
Here is a quick breakdown of what they don’t do, and the very few concerns they do present.
Harmless to People and Pets
- No Stinging or Disease: Box elder bugs do not sting and are not known to carry or transmit any diseases to humans or pets.
- No Biting (Almost): While technically capable of piercing skin, they are not aggressive and do not seek to bite people. In extremely rare cases, a bug might defensively “test” a person’s skin, leaving a minor, temporary red mark similar to a mosquito bite.
- Safe for Pets: If a pet, like a curious dog or cat, eats a box elder bug, there is generally no serious danger. They are non-toxic, though their foul taste may lead to a bit of temporary stomach upset or vomiting, which usually discourages the pet from eating another one.
No Threat to Property or Structures
- No Structural Damage: Box elder bugs do not chew wood, eat fabric, or bore into materials. They are not like termites or carpenter ants. They simply seek a warm, dry place to rest during the winter (overwintering) inside wall voids, attics, or behind trim.
- No Indoor Breeding: They do not reproduce inside your home. They must wait for warmer spring temperatures to emerge and lay their eggs on their host trees outside.
The Real Nuisance Issues
The only problems box elder bugs truly cause stem from their behaviour in large numbers:
- Staining: If you crush a box elder bug, it releases a liquid that can leave a persistent, noticeable reddish-orange stain on clothing, carpets, window sills, and light-coloured surfaces.
- Odour: Crushing them also releases a foul odour, which is why vacuuming them is the recommended removal method.
- Uninvited Guests: The sheer annoyance of having hundreds of insects suddenly appear inside your living space on a sunny winter afternoon or emerging from hibernation in the spring is enough to warrant control measures!
If you are seeing these bugs, you can rest easy knowing they are not dangerous. Your efforts can be entirely focused on preventing their entry and keeping them outside where they belong.