Eastern Box Elder Bug

Eastern Box Elder Bug (Leptocoris trivittatus) is a native insect common to the eastern parts of Canada and the United States that is largely considered a common household pest.   

Life Cycle and Description

In the spring, overwintering insects lay their eggs on stones, leaves, grasses, and shrubs. The hatched nymphs are red in colour, much like the European fire bug. In the next stage of their life cycle, the adults are dark/black in colour with more distinct orange markings. 

These insects are active during the day throughout the spring and summer months and tend to hide in the evenings and overnight. As fall approaches, they tend to congregate, sometimes in potentially large numbers, on sunny-facing sides of buildings, trees, and stone walls as they warm themselves in the sun. This is also the time of year that they begin finding their way into homes or other structures as they attempt to find places to hibernate and overwinter. Box elder bugs are mostly an annoyance to homeowners because of their behaviour.

Hosts and Behaviour

Both nymphs and adults of box elder bugs feed on the fallen seeds of the female Manitoba maple or box elder tree (Acer negundo) well into the fall. These insects are harmless to humans and will not damage any living plant material or trees. Any damage that can be attributed to these insects is in the form of their excrement.

Specific Management Practices for Control

Because this insect does not harm the health of trees, it is not considered a Forest Health concern; therefore, the City of Toronto does not provide treatments for box elder bugs. Urban Forestry recommends homeowners follow the management practices listed below.

• Focus should be on preventing the insects from accessing homes and buildings. The best way to keep box elder bugs out of a building is to make sure that there are no entry points. Filling gaps around windows and doors with weather stripping, repairing or filling holes in foundations and using window and door screens will help to prevent their entry.  In some cases, completely sealing up the home may be next to impossible. If the insects do manage to find their way into the home, simply vacuum them up and dispose of them.
• The use of an insecticide labelled for box elder bug control could be applied by treating the exterior of the building at the time of the swarming in the fall. Treat the siding, windows, doors and the foundation of the building with an insecticide. Many pest control companies provide services that help control insects around homes.
• True bugs, such as red firebugs or Eastern box elder bugs, especially the nymphs, are easily drowned. Regular use of high-pressure water from a garden hose sprayed directly on the insect congregations can be effective.
• An alternative to synthetic insecticides is a mixture of soapy water that can be used to spray the insects directly, which has been shown to have some knock-down effect:

Recipe:

• 2 tbsp. of liquid dish soap
• 1 litre of water
• 2 tbsp. of cooking oil (IE., canola, olive)

Instructions

Mix ingredients and put into an empty spray bottle or hand pump sprayer. Spray insects directly, ensuring to cover them as best as possible with the solution to achieve the best results. Spray as often as necessary. Soap only kills the bugs that are being sprayed and has no residual effects once it is dry.

The Ontario Cosmetic Pesticides Ban Act prohibits pesticides from being used for cosmetic purposes on lawns, vegetable and ornamental gardens, patios, driveways, cemeteries, and in parks and school yards. There are no exceptions for pest infestations (insects, fungi or weeds) in these areas, as lower-risk pesticides, biopesticides and alternatives to pesticides exist. Over 95 pesticide ingredients are banned for cosmetic use.