Beware of Box Elder Bugs
Adult box elder bugs are about ½ inches long, black with orange or red markings, including three strips on the prothorax, the area right behind the head. Their wings lay flat over their bodies, overlapping each other to form an ‘X’. The immature nymphs are 1/16th-inch long and bright red when they first hatch. As they grow older and become larger, they are red and black. You can potentially see all stages at any given time during the summer.
- Boxelder bugs are a nuisance in and around homes from fall through early spring.
- The bug overwinters as an adult in protected places such as houses or other buildings.
- Removing female Boxelder trees is the most permanent solution to the problem, although this may not be practical or desirable.
- Laundry detergents offer safe, effective control when applied directly to the insects.
Types of Control
The most permanent solution to the box elder bug problem is the removal of female box elder trees from a neighborhood, although this may not be practical or desirable. Because box elder bugs usually overwinter near the trees that they feed on, the removal of one or two problem trees may help. Screening or sealing cracks or other entrances into the dwelling is important. Once box elder bugs have entered the home, control becomes more difficult.
When the bugs begin to congregate on building exteriors, these areas (including all resting and hiding places) may be sprayed with residual insecticides. However, most insecticides registered for treatment of building exteriors are not that effective against box elder bugs. Laundry detergent and water mixes are cheap, safe and effective when applied directly to box elder bugs. Drawbacks of detergent sprays are that they will kill only if they contact the insect directly, and they may damage vegetation.
Use a vacuum cleaner to control bugs that have entered the house. Household insecticidal aerosols and many household spray cleaners also are effective when applied directly to individual Insects. These measures provide temporary relief only. Bugs may continue to enter the home as they move about on warmer days throughout the fall, winter and early spring. Nuisance infestations should be finished by late May, as the box elder bugs have either died or moved back to the host trees.
Biology and Life Cycle
In Minnesota, box elder bugs emerge from overwintering sites during spring as the weather starts to warm up. Adults feed on low vegetation and seeds on the ground during spring and early summer, and begin mating a couple weeks after they started feeding. Starting in mid-July, they move to female seed-bearing box elder trees, where they lay eggs on trunks, branches, and leaves. They are rarely found on male box elder trees. There is no noticeable feeing injury to these trees. During years of high populations, you may find nymphs on the ground or in gardens feeding throughout the summer.
During late summer and fall, box elder bugs start to leave the trees from where they were feeding to find protected areas for the winter. Although nymphs mat be present in the fall, only fully grown adults survive the winter. Adult box elder bugs typically can fly several blocks, although in some cases they can travel as far as two miles.
The best management of Boxelder bugs us prevention. Take steps to keep them from entering your home from the start. You can partly do this through exclusion though it largely depends on how your home was constructed. Make any repairs by the end of August.
For all Homes
- Repair or replace damaged windows and door systems.
- Repair or replace damaged screens in roof and soffit vents, and in bathroom and kitchen fans.
- Seal areas where cable TV wires, phone lines, and other utility wires and pipes, outdoor facets, dryer vents and similar objects enter buildings.
- Seal with caulk or for large spaces use polyurethane expandable spray foam, copper mesh, or other appropriate sealant.
- Install door sweeps or thresholds to all exterior entry doors. Install a rubber seal along the bottom of garage doors.
You may want to supplement non-chemical methods with an insecticide treatment around the exterior of your home, especially if large numbers of box elder bugs are present and/or you have a history of box elder bug invasions. The best time to spray is late summer and fall when box elder bugs are first clustering around the outside of buildings.
You can treat you own home by using an insecticide labeled for the exterior of buildings. Examples of common names of active ingredients available to the public are:
- Lambda cyhalothrin
CAUTION: Read all label directions very carefully before buying insecticides and again before applying them. Information on the label should be used as the final authority.
You may also consider hiring an experiences pest control service to treat your building exterior. They have the necessary experience to successfully treat your home.