As the weather warms up, homeowners may notice an increase in the number of boxelder bugs and Asian lady beetles that "mysteriously" appear inside their homes. All accidental invaders found inside at this time of the year entered the building last fall through cracks and openings, and spent the winter hibernating behind exterior siding and in attics, wall voids, window/door casings, and similar protected areas. With the onset of warmer weather, the insects become active and emerge from their overwintering sites. As they attempt to escape to their natural habitat outdoors, some get mixed up and move inward into living areas, emerging from beneath baseboards, behind window and door frames, from within sash-cord openings, and around light fixtures and vents.
Overwhelmed homeowners often want immediate and complete relief from the annoyance of accidental invaders. Unfortunately, this simply isn't possible, since the bugs are emerging from hidden areas that are inaccessible to insecticides. Household foggers ("bug bombs") will not penetrate and control pests in these protected areas. Residual sprays generally kill invaders too slowly to be considered successful.
The best way to dispose of ladybugs and boxelder bugs appearing indoors is with a vacuum cleaner. Both insects tend to emit substances that can stain surfaces, making a broom less desirable. Repeated vacuuming may seem inefficient and monotonous, but it remains the most practical control.
The frustration of invader insects is temporary, as the nuisance will run its course as the weather warms. Ladybugs and boxelder bugs typically do not bite, sting, or carry diseases, nor do they infest food, clothing or wood. They do not reproduce indoors. Lady beetles do not feed on people though they infrequently pinch exposed skin.
Another insect you may see wandering in the house this time of the year is the larder beetle. Larder beetles aren't really an accidental invader that is overwintering in the walls. Larder beetle adults and larvae feed on the dead insects in the walls of the house. Although you may see a lot of lady beetles and boxelder bugs alive, many more do not survive the winter and are dead in the walls of the house. Isn't that an image you want to think about? Larder beetles serve as nature's recyclers and feed on these dead insects. The larder beetle adults are usually what people notice wandering about in the house.
What can be done in the future to prevent this insect invasion from happening? With accidental invaders, the most effective management option is to prevent them from getting inside the home by sealing cracks, gaps and openings on the outside before they wander in during late summer. Application of pyrethroid insecticides such as permethrin or esfenvalerate to the outside of buildings may help prevent pest entry. Treatment must be applied before the insects begin to enter buildings to be effective (mid to late September). Homeowner insecticides other than pyrethroids usually do not provide satisfactory prevention.
So hang in there and these uninvited guests will soon be gone. If you need any more information, just call the Extension Office in Cherokee at 712-225-6196. We have publications that will suggest ways to control the bugs in your house and yard.