Boxelder Bugs

boxelder bugsBoxelder bugs are common pests over much of the United States. Adults are about 1/2 inch long. They are bright red or black with narrow reddish lines on the back.


Box elder bugs feed principally by sucking juices from the box elder tree, but are sometimes found on other plants (especially maple trees). They do very little damage to the trees they attack, but at certain times of the year, they can become a nuisance. Box elder bugs develop by gradual metamorphosis, from egg to nymph, then to adult.

When box elder bugs build up to large populations and invade a home they are usually pests only by their presence, although their piercing-sucking mouthparts can sometimes puncture the skin, causing slight irritation. Sometimes, they leave fecal material that may stain resting sites such as curtains. They may be seen to gather around the foundations, bases of trees, along foundational walls and fence rows during the fall months.

They are part of a group of insects that are called "fall invaders" are are occasional invaders.

Adult box elder bugs will enter structures into the fall, seeking winter shelter.

Boxelder bugs enter structures in the fall months and "overwinter" in protected areas. They seek shelter in protected places such as houses and other buildings, cracks or crevices in walls, wall voids, attics, doors, under windows and around foundations, particularly on the south and west exposures. Box elder bugs can come out even during the dead of winter when it is cold outside and the sun is shining.

They will then emerge in the spring to seek out host trees on which to feed and lay eggs.

Prevention-How to get rid of boxelder bugs

  • Prevention is key to getting rid of boxelder bugs. Spray the exterior walls of your home in the fall with a residual insecticide to stop them from over-wintering if you have not sprayed earlier. If you treat earlier (early summer months), you have the best chance to control the immature stages of boxelder bugs. Ideally spray twice, once in the spring-early summer months when they emerge and once in the fall when they seek shelter. Once they have come inside to overwinter, total control is close to impossible as locating all infested voids is difficult.
  • If your home has a prior history of boxelder bugs, find and seal as many exterior cracks as possible during the summer.
  • The easiest way to remove boxelder bugs, once they are indoors, is a vacuum cleaner.
  • You can also use an insecticide spray around the baseboards and window seals on the interior of the home to further control the bugs. Interior spray should be the last line of defense however because it won't stop the bugs from coming into the home. The boxelder bug will eventually die after it comes into contact with the insecticide.

To help prevent box elder bugs, cluster flies, lady bugs and similar pests from entering in the fall, spray fast-acting synthetic pyrethroids such as the ones listed below on the exterior walls of the structure. Spray around eaves, attic vents, windows, doors, under-fascia lips, soffits, siding (including under lips) and any other possible points of entry, concentrating on the south and the southwest sides. It is also helpful to spray around the perimeter.
Shady areas are less likely to attract box elder bugs.

LambdaStar UltraCap 9.7 and D-Fense SC will dry without a visible residue, while Cyper WSP can be seen against darker surfaces. Both products will last 2-3 months on the surface once sprayed.

Lambdastar ultracap 9.7LambdaStar UltraCap 9.7
1 pt of LamdaStar UltraCap 9.7 yields 20-40 gallons (Mix 0.5 oz per gallon (makes 32 gallons for box elder control)


d fense scD-Fense SC
1 pt of D-Fense SC yields 11-22 gallons of finished product. For box elder control, mix 1.5 oz per gallon (yields 11 gallons)


cyper wspCyper WSP -1 envelope yields 4 gallons (mix 1 inner packet per gallon of water).


Mechanical means of exclusion

Exclude Boxelder bugs during the summer months. Concentrate on the south and west exterior walls. Avoid excluding them during the months when they are mostly likely inside so you do not seal them inside. If you seal them inside, they may enter interior rooms in large numbers.
  • Plug weep holes with wire mesh.
  • Foundation and attic vents should be equipped with tight fitting screens
  • Fix broken window screens and door jams
  • Plug cracks in the foundation or roof with exclusion materials
  • Caulk cracks and caulk around utility lines