Tree Maintenance

Box elder bug

Boxelder swarm on treeThe box elder bug is a common household, nuisance pest. There is no risk to human health or to the environment from this pest, nor is it a tree pest that endangers the health of trees on which it is found. This insect is associated with box elder or Manitoba maple (Acer negundo) trees. The bugs are attracted to the seed of the female trees. In the fall they congregate in areas where Manitoba maple trees are present and start to look for shelter for the winter season. Box elder bug outbreaks have a seasonal and cyclical character. Dry, hot summers and autumns are favourable weather conditions for them. There is no effective method to control them in the natural environment on a city-wide scale. Download eastern box elder bug information sheet (PDF).

There are a number of things a resident can do to mitigate the infestation on their property:

  • Preventing box elder bugs from entering the home is the single most important defense. Seal doors, window frames and cracks in the walls. Screen off vent pipes and other openings with a fine screen.
  • Remove debris, wood piles and other potential places box elder bugs will gather to survive the winter.
  • Box elder bugs found gathering on trees or the sunny side of houses can be sprayed away with a garden hose.
  • Spray swarms of the bugs with insecticidal soap, available at most garden centers; repeated spraying is often necessary.
  • Vacuum colonies from the sides of houses into a shop-vacuum. Pour a soapy water over insects to suffocate them.
  • Do not squish them; squished, they emit an odour that attracts more bugs to the location.
  • Dust the bottom of windows and doors and pathways with diatomaceous earth. This product is available at most garden centers.
  • In some cases, female seed bearing Manitoba maple trees can be removed to decrease the number of box elder bugs. This is not a viable solution in areas where Manitoba maple trees are numerous. Adults can fly long distances looking for new sources of food and breeding sites. The removal of individual female Manitoba maple trees is not recommended unless they are found isolated in small numbers on the property.

If the problem persist and become intolerable, the resident is advised to call a pest control company.

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