Pest description and damage About 0.5 inch long and dark color with red longitudinal lines on the back. Annoying when they cluster on and migrate into dwellings. Boxelder bug populations vary considerably from year to year depending on environmental conditions.
Inside homes, insecticides have limited value and are not recommended. Use a vacuum cleaner to pick up bugs in building interiors. Prevent bug entry by repairing screens and caulking around windows and doors, screen soffit, corner trim and attic vents, etc. Sealing is best done during the summer months when the bugs are not present.
Insecticide treatment has not been very successful. Residual sprays (by a pest control operator) where bugs congregate on building sides and near the foundation may reduce entry indoors but will not eliminate the insects. A professional tree service may treat infested trees near the structure, though adult bugs can fly for several miles from their feeding sites.
For further information:
How to Manage Pests/Pests in Gardens and Landscapes/Boxelder Bug. University of California. http://ipm.ucanr.edu/PMG/PESTNOTES/pn74114.html