Box Elder Bugs
Facts, Identification & Control
What do box elder bugs look like?
- Black & red bodies – the bodies of box elder bugs are black in color and are marked by red lines along the thorax and sides.
- Wings – their wings are flat and red
- Size – Box elder bugs measure between 11 to 14 mm long
Behavior, Diet & Habits
Trees in warmer months
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.
How do they get in the house?
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.
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.
Sunny side of buildings
They usually appear on sunny sides of buildings in the fall.
Move inside during winter
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.
How to Get Rid of Boxelders
Get rid of host trees
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.
In some homes, chemical product treatments (extermination) in strict accordance with the product’s label directions might be necessary. Typically chemical products are applied in late-summer and early-fall.
- Read more details about box elder bugs in the house.