Box Elder Bugs cause concern in the autumn when they gather in considerable numbers on the warm outside walls of homes and sometimes find their way into houses looking for a suitable place to over-winter.

When they gain entry to buildings through cracks or other openings they remain in wall cavities and will occasionally emerge inside the home in the spring.  They will not breed indoors, so there is no danger of starting an “infestation”.

They cause no structural damage whatsoever, but they can  “spot” interior furnishings with their droppings. They can’t bite, they don’t eat anything on the inside of your house, including house plants.  They won’t harm you, your family or your pets.

Prevention and control

Insecticides are not very effective and box elder bugs will only be around until the weather gets cold – so the best solution may be to ignore them until they go away.  In extreme cases you may want to apply a residual insecticide to exterior walls in the fall where the bugs are congregating – this will tend to discourage them from landing.  Here are a few suggestions to prevent the bugs from entering your home:

Adjust or install tight-fitting door sweeps or thresholds at the bottom of all exterior entry doors. Gaps of 1/8″ or less will permit entry of insects. Garage door bottoms should be fitted with a bottom seal constructed of rubber (vinyl seals poorly in cold weather). Gaps under sliding glass doors may be sealed with foam weatherstripping.

Seal utility openings where pipes and wires enter the foundation and siding, e.g., around outdoor faucets, receptacles, gas meters, clothes dryer vents, and telephone/cable TV wires. Holes can be plugged with caulk, cement, urethane foam, steel wool, or copper mesh.

Caulk cracks around windows, doors, siding, and facia boards. Use a good quality silicone or siliconized acrylic latex caulk. Although somewhat less flexible than pure silicone, siliconized latex-type caulks clean up with water and are paintable. Caulks that dry clear are easier to use than pigmented ones because they cover mistakes.

Repair damaged window screens and install insect screening behind attic vents.

Home Remedies

Indoor Treatment. Vacuuming up the bugs and discarding the contents of the vacuum bag when finished is a good effective housekeeping method. (If bugs are left inside the vacuum, they may crawl out in the storage place.) Tightening up the routes of entry the bugs use by caulking or screening is a more permanent solution.

Exterior Treatment.  An 80/20 mix of water and liquid dish soap sprayed onto the bugs works well.

Insecticides

Indoor Treatment. Insecticide foggers or sprays are generally NOT recommended for eliminating box elder bugs indoors. Box elder bugs need to be sprayed directly, or have to crawl over treated surfaces, in order for the insecticide to be effective. Such applications create pesticide residues on walls, countertops, and other exposed surfaces. A vacuum cleaner is more sanitary and effective. Attempting to kill overwintering bugs in wall voids is difficult and rarely justified.

Exterior Treatment.  Insecticides can be used effectively on the trees to control the nymphs while they are actively feeding. Either the insecticide malathion or carbaryl may be recommended. The homeowner may spray a small number of trees, but large trees and large groups of trees should be done by a certified pesticide applicator. Cyfluthrin of deltametrin may be used outdoors to spot treat accumulations of box elder bugs.

Brand Names- insecticides

• Carbaryl (Sevin): Garden Tech- Sevin Bug Killer, Ortho- Bug-B-Gon Insect Killer.
• Cyfluthrin: Raid- Max Roach & Ant Killer, Bayer- Advanced Garden Multi-Insect Killer, Tempo, Baythroid, Laser
• Deltamethrin: Viktor- Ant Killer, InterCept- Home & Garden Insect Control, Green Light-Roach, Ant & Spider Control, Delta-Eight, Deltagard, Enforcer.
• Malathion: K-Gro- Malatinion Insect Spray, Ortho- Malathion Insect Spray, Green Thumb- Malathion Insect Killer, Real-Kill- Malathion Insect Killer, Eliminate- Malathion Insect Spray

BE SURE TO FOLLOW THE MANUFACTURERS DIRECTIONS ACCURATELY WHEN USING ANY PESTICIDE.