All About Box Elders

Box elders are small, tree-dwelling insects of the family Rhopalidae. They are true bugs, which means they belong to an order (Hemiptera) of insects that includes cicadas, aphids, planthoppers, leafhoppers, and shield bugs. Box elders earn their name because they often live in boxelder trees, though they also live in maple and ash trees. Box elders are found in the western and midwestern United States.

Box elders are black in color and have red lines along the thorax sides. Their wings are flat and bright red in color. They are almond-shaped with antennae that are roughly one-third of their body length. They measure between 14 millimeters and 18 millimeters in length.

Box elders are most active during the spring and summertime, when they come out of hibernation. These bugs eat mostly juice from host trees, flowers, leaves, and twigs — which is why they can be a destructive issue for outdoor properties. Though they feed on organic matter mostly found outdoors, box elders still often enter indoor spaces in search of cooler temperature in the summers. (Sometimes, they’ll stay through the winter to hibernate in the warmth.) Box elders emit a foul odor and leave behind unsightly stains when crushed — which is why they are considered a particularly undesirable indoor pest.

What Causes Box Elder Infestations?

There are two types of box elder infestations: outdoor infestations and indoor infestations. Outdoor box elder infestations take place when box elders populations nest and grow within a tree (or several trees). If left to persist, outdoor box elder populations can consume a large quantity of plant matter on a property and cause some damage to their host trees. Indoor box elder infestations occur when box elder bugs move in large quantities towards an indoor space in search of more comfortable shelter. Box elders will often collect near doors or windows, attracted to cooler, climate-controlled air. The insects can find their way into indoor spaces through holes around windows, spaces under doors, and other small openings in roofs or walls. Keeping your property watertight will help keep box elders out during their active seasons.