Boxelder Bug Control

E-451 (Revised), July 1991

Dean K. McBride, Entomologist, NDSU Extension Service

The boxelder bug is the common red and black insect which clusters around boxelder trees during the summer.

Boxelder bugs normally feed on leaves, flowers and seed pods of boxelder trees and other trees of the maple family. They cause minimal damage to trees.

They may number into the thousands on some trees, usually on the female or seed bearing trees. They also may be on male boxelder trees and other trees and plants.

Large numbers of the bugs sunning themselves is a common site during the warm part of fall and early spring days. Such activity occurs on south and west sides of buildings when the bugs come out from the cracks and crevices used for shelter during the winter.

This bug is annoying chiefly as a household pest. Crawling on persons, congregating in the windows, soiling window curtains and drapes, and flying about in occupied rooms, boxelder bugs arouse general disgust, even though they produce no odor nor damage or injury to wood, foods, humans or pets.

Description

The adult boxelder bug is a bright-colored insect with three red lines down the prothorax. The harder portions of the front wings have red margins. The young (called nymphs) are easily recognized since they are wingless and are a more brilliant red than the adults. Mature nymphs and the winged adults are about 1/2 inch long and about one third as wide.

The adults and nymphs have piercing, sucking mouthparts. In the summer they normally feed on the underside of the leaves of boxelder trees.

Life Cycle

Tiny red eggs are laid in the spring by female bugs that have survived the winter. Nymphs hatch from the eggs and pass through five distinct growth stages before becoming winged adults.

The red nymphs acquire black markings when they are about half grown. Adult boxelder bugs are produced from midsummer until late fall. With the arrival of cold weather, the adults seek shelter. Many crawl into cracks around the doors and windows. Large numbers of the bugs eventually get into homes, school rooms and offices where their presence is very unwelcome.

Control

Boxelder trees are the chief source of food for boxelder bugs, so home owners might benefit by removing these trees, especially the female or seed bearing trees. Also, don't plant or allow these trees to become established. Take the following preventive measures if you don't want to remove the trees:

• Eliminate hiding places such as piles of rocks, boards, leaves and general debris close to homes.
• Repair and caulk places where bugs may enter the home, such as cracks around doors, windows and siding and in the foundation.
• Rake leaves and remove weeds, grass and other protective debris from a strip 6 to 10 feet wide around the foundation, particularly on the south and west sides of the structure. Such a barrier strip discourages congregations of bugs near the foundation.

Spray recommendations outside homes and buildings: When concentrations of boxelder bugs are seen, either on the trunks of boxelder trees or on the foundation and sides of a building, apply a spray directly on the bugs and on the area where they are observed. Use any of the following insecticides:

• 2% carbaryl (Sevin)
• 0.5% diazinon
• 0.5% chlorpyrifos (Dursban)

Check the label on the insecticide container to make certain both the insect and the site are listed before using.

Thoroughly apply a residual spray of any of the insecticides to the surface of the barrier area and to the foundation and sides of the buildings. This will help control individual boxelder bugs and other migrating insects. Additional spray applications may be needed.

Control recommendations inside homes: Control boxelder bugs that come through the walls into the heated rooms of the home by hand collecting, fly swatter, vacuuming, or using a household aerosol containing pyrethrins, resmethrin, or other materials labeled for this use.

Caution

Handle insecticides with care. Follow directions on the label. Keep insecticides off skin and out of eyes, nose and mouth. Wash immediately with soap if concentrates are accidentally spilled on skin and after completing spray application. Store unused insecticides in a dry area, out of reach of children and pets.

E-451 (Revised), July 1991