Boxelder bugs (Boisea spp.) are flashy-looking insects with their 1/2-inch-long, deep gray to black bodies and bright red markings. These North American natives prefer feeding on the leaves, seeds and flowers of female boxelder trees (Acer negundo), which grow in U.S. Department of Agriculture plant hardiness zones 2 through 10. Boxelder bugs cause no significant damage to plants, people or pets, but can become a nuisance around and in homes from fall until early spring. You can use several different methods to get rid of outdoor boxelder bug populations.
1 Remove piles of leaves, rocks, lumber, grass and other debris. Boxelder bugs shelter from the heat of the day and overwinter in this type of material. Removing hiding places deters them from your garden and yard.
2 Rake up boxelder tree seeds that fall to the ground. These seeds are the pests' favorite food and the bugs will fly up to several miles to feed on those lying on your lawn.
3 Handpick boxelder bugs when they appear in small numbers on plants or buildings. Drop them into a bucket of soapy water to drown the pests.
4 Spray any boxelder bugs you spot lounging on tree trunks, walls, fences or sidewalks with a strong blast of water from your garden hose. This washes the pests away and drowns them.
5 Pour hot water -- 165 to 180 degrees Fahrenheit -- directly on the pests. Avoid spilling the hot water on any desirable plants or grass in the area, as it will kill the plants.
6 Mix 1/2 cup of mild liquid dish soap into 1 gallon of water. Pour the mixture into a squirt bottle and spray directly onto the pests as needed. The soap solution only kills bugs on contact and offers no residual effects.
7 Mix about 1 1/2 fluid ounces of carbaryl-based insecticide in 1 gallon of water. Put it in a garden sprayer and thoroughly cover the tops and undersides of leaves, twigs, stems and trunks. Repeat applications when needed, up to four times a year, but allow at least seven days to elapse between treatments.