Box Elder Bugs

Facts, Identification & Control

Latin Name

Boisea trivittata


What do box elder bugs look like? box elder bug
The bodies of box elder bugs are black in color and are marked by red lines along the thorax and sides. Their wings are flat and red. Box elder bugs measure between 11 to 14 mm long.

Behavior, Diet & Habits

Box elder bugs do not nest indoors year-round. Rather, they make their homes in box elder, maple and ash trees during warmer seasons and migrate into buildings and homes to find shelter for the winter.They enter through small cracks and crevices within the building, and remain inside, hibernating, through fall and winter. They emerge when heat sources within the building are high and can be located in the warmest areas of a structure’s walls. While they do not cause damage to buildings, their droppings are unsightly and leave stains on furniture and linens.

Adult bugs live and breed on the leaves of box elder trees, laying their eggs in spring. They feed on soft parts of box elder trees, including leaves, flowers and new twigs. They also extract juices, causing minimal to substantial damage to their host tree. Find out more about box elder bug behavior and whether they bite.


The eggs of box elder bugs are reddish brown in color, allowing them to stay well hidden in the bark of the host tree. After a few days, the eggs hatch into red and gray nymphs, which eventually mature and begin the breeding process again. Mature box elder bugs can be found gathering in large numbers on branches and boughs. Concentrations will be heaviest in areas receiving sufficient sunlight. Read more details about the box elder bug life cycle.

Signs of a Box Elder Bug Infestation

Like many overwintering pests, the most startling sign is the bugs when they invade in staggering numbers. They usually appear on sunny sides of buildings in the fall. They invade the voids of the building to overwinter. While overwintering, they do not feed or reproduce. Find out more about box elder bug infestations.


To stop box elder bugs from multiplying, it is often helpful to remove their host trees from the area surrounding your home, but the adults can still fly from locations off the property. If you choose to plant box elder trees in your yard, choose male trees: (non-seed-bearing) since female box elder trees are more susceptible to infestation. However, box elder trees are not recommended for ornamental planting. These insects can also enter through windows and doors; ensure that these close properly and utilize screen doors to keep box elder bugs from entering. Read more details about box elder bugs in the house.

How Orkin treats for box elder bugs

Box elder bugs become a pest nuisance when they congregate on the exterior of buildings and eventually find a way inside to overwinter. While box elder bugs are somewhat easy to identify, it is best to contact your pest management professional for treatment advice and recommendations since boxelder bug treatment must be an integrated program that includes both non-chemical and chemical methods.

Exclusion is an effective, long-term treatment method even though it may be labor intensive. Since box elder bugs become most problematic when they get inside buildings, keeping them out is vital. Some examples of important exclusion activities include:

  • Repairing damaged windows and door screens
  • Installing door sweeps on exterior doors
  • Installing or repairing screens in roof and soffit vents
  • Sealing holes or gaps around places where cables, wires or plumbing enters the building
  • Plugging gaps at doors, windowsills, roof joints, and fascia boards. Checking for and sealing gaps and cracks where different building materials meet. For example, where siding meets the brick exterior or foundation.

However, there may be some locations where exclusion is not practical, so using chemical product treatments (extermination) in strict accordance with the product’s label directions might be a necessary adjunct to exclusion, especially if large numbers of boxelder bugs are present and/or there is a history of boxelder bug invasions. The best time of year for using chemical products is late-summer and early-fall when boxelder bugs are first clustering around the outside of buildings. Also, if boxelder bugs do get inside a building, using vacuums rather than chemical methods is preferred.