Boxelder Bug

The boxelder bug (Boisea trivittata), also known as the maple, is a small, black bug featuring distinctive red or orange markings on its back. It is a common pest but not a major threat to homes or agriculture.

Host Plants

The boxelder bug feeds primarily on the seeds and leaves of the boxelder tree (Acer negundo), from which it gets its name. Boxelder is dioecious, and individual trees produce either male or female flowers. Boxelder bugs primarily feed on clusters of drooping, seed-bearing racemes formed from female flowers, making them their main food source. These true bugs also use other species of maple and occasionally ash trees as hosts. Their diet can extend to fruits, particularly plums, cherries, peaches, grapes, strawberries, and apples, where they pierce the fruit’s skin to lay eggs.

Regions impacted

Boxelder bugs are native to much of North America and can be found wherever their principal host, Acer negundo, occurs.

Description

Adult boxelder bugs measure about 0.49 inches (12.5 millimeters) long. They are black with reddish or orange markings on their back. Their wings lay flat over their bodies, overlapping to form an ‘X’. The young, called nymphs, are 1/16th of an inch and bright red when they first hatch.

Life Cycle

Boxelder bugs, like all insects, go through a life cycle that includes multiple stages.

Egg: The boxelder bug life cycle begins in the spring when the female lays small, red eggs on leaves, stones, grasses, and other places near female boxelder, maple, or ash trees. The eggs are often placed in the cracks or crevices of bark, protected from predators and the elements.

Nymph: After about two weeks, the eggs hatch into nymphs, which are bright red. Nymphs are immature versions of adult bugs but lack wings and are smaller in size. As the nymphs grow, they molt (shed their skin) several times, each time growing larger. During this stage, nymphs depend on the host trees’ seeds for nutrition.

Adult: After several molts throughout the summer, the nymphs eventually become adult boxelder bugs. This typically occurs by mid-July.

In the fall, adult boxelder bugs seek out places to overwinter, often resulting in their intrusion into homes. During the winter, they remain largely inactive, but on warm winter days, they can become active again and may be seen congregating on warm, indoor surfaces.

Once the weather starts to warm in the spring, the adults emerge from their overwintering locations to lay eggs and repeat the cycle.

In general, boxelder bugs have one generation per year, meaning the adults that emerge in the spring are the offspring of the adults from the previous year. However, there may be more than one generation per year in warmer climates.

Damage and Detection

Damage:

Boxelder bugs are not known to cause significant damage to their host plants or homes where they seek shelter. They do not chew leaves but suck the juice from the leaves, flowers, and seed pods of boxelder, maple, and ash trees. This can result in discoloration and minor distortion of leaves, creating a cosmetic nuisance but not generally causing serious harm.

When feeding on fruit trees like apples, they can pierce the fruit’s skin, causing small indentations or deformities, although they do not cause the type of extensive damage that some other fruit pests can cause.

Although boxelder bugs don’t physically damage homes, their droppings can stain light-colored surfaces. They also release a pungent and unpleasant odor when crushed or disturbed, which can be a nuisance to homeowners.

Detection:

Detecting boxelder bugs is relatively straightforward due to their distinct physical characteristics and behavioral patterns.

• Appearance:  Boxelder bugs can be identified by their distinctive black and red coloration, elongated oval shape, and three distinct red lines on their thorax.
• Behavior: Boxelder bugs are most visible in the spring when they emerge from their overwintering sites and in the fall when they are seeking places to overwinter. During these times, they often congregate in large numbers, particularly on the sunny sides of trees, rocks, and buildings, which makes them easy to spot.
• Indoor Infestation: In winter, boxelder bugs may enter homes and other buildings to overwinter. Seeing these bugs in your home, particularly as the weather gets colder, clearly shows their presence. Check for them around windows, doors, in the basement, and in other areas where they might find shelter.

While boxelder bugs can be a nuisance, especially when they enter homes in large numbers, they are generally not considered a serious pest. They do not bite or sting, they do not carry diseases, and they do not cause significant damage to plants or structures. Most control measures focus on preventing their entry into homes and dealing with them once they’re inside.

Prevention and Control

Boxelder bugs are generally harmless but can become a nuisance when they invade homes in large numbers.

Prevention

• Seal Entry Points: Seal cracks and crevices around windows, doors, siding, and utility pipes with caulk or other suitable materials. Install door sweeps on exterior doors and repair or replace damaged screens on doors and windows.
• Fallen Seeds: Clearing and disposing of fallen seeds from beneath or near host trees eliminates a food source for adults as they emerge in spring.
• Remove Host Trees: If practical and appropriate, consider removing female boxelder trees from the vicinity of the home. Boxelder bugs feed on these trees, so removing them can help reduce their populations.

Control

• Physical Removal: If boxelder bugs have already entered a building, physically removing them is often the best option. A vacuum cleaner can be an effective tool for this. After vacuuming the bugs, be sure to remove the bag or empty the canister outside to prevent the bugs from escaping back into the building.
• Insecticidal Soap: If there is a large infestation on a host tree, you may use insecticidal soaps. These are considered relatively safe and can reduce the number of nymphs and adults when sprayed directly on them. This kills only those insects that are in direct contact with the spray. Repeated applications may be necessary if new aggregations appear.
• Professional Pest Control: If the infestation is too large or widespread for you to handle on your own, consider hiring a professional pest control service. They have access to professional-grade insecticides and the expertise to apply them safely and effectively.

Remember, boxelder bugs are more of a nuisance pest than a damaging one. They don’t bite or sting, and they don’t cause significant damage to homes or plants. Their main downside is their tendency to invade homes in large numbers, which can be disruptive and unpleasant. The strategies above can help keep their numbers in check.