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There are many signs that point to the fact that winter is on its way. We have had a killing frost. For me, a killing frost on September 16 was the earliest since 1983 when I first began keeping records. Other signs include falling leaves, woolly caterpillars, yellow jackets, Asian beetles, and boxelder bugs crawling into my coffee cup. Everything is two to three weeks ahead this summer except for boxelder bugs. They have been around all summer.

Jeff Hahn, Assistant Extension Entomologist, has written many articles on boxelder bugs over the years. I even read an article by Rod Elmstrand back when he was the Chisago County agent. The only thing that has changed on the boxelder bug is the chemicals used to control them as you can no longer use diazinon.

Boxelder bugs feed on low vegetation and seeds on the ground during the spring and early summer. These black and orange bugs move to the female seed-bearing boxelder trees, starting in mid-July.

Eggs are normally laid on the trunk, branches, and leaves of the trees and are found almost entirely on flowering and seed-producing boxelder rather than on male boxelder trees.

During late summer and fall, the bugs begin leaving the trees to find protected areas for the winter. Although many young insects may be present in the fall, only full grown bugs survive the winter.

As the weather cools, these bugs will push into cracks and enter houses near foundations. Many crawl under siding or shingles and get into wall voids and attics. They may enter through doors, windows, vent openings, and other accessible areas.

During the winter they are generally inactive. However, during warm, sunny days some will leave the walls and invade the interior of the home. Although they do not breed in homes they are still a real nuisance as they spot curtains and fabrics. Some may seek moisture around flower pots, but they don't damage plants. They may even lay eggs in the soil but immature bugs do not survive winter. You can identify a boxelder tree by its ragged appearance and the seeds are easy to spot. The winged seeds are similar to maple seeds as they appear in small clusters on the tree.

Removing the female (seedbearing) boxelder trees on which the bugs feed is not a practical solution since they can fly several blocks. Boxelder trees are real survivors as the root will keep growing even after the tree is cut down. I'm afraid that a sure sign that the world is coming to an end is when a disease or insects destroy the boxelder tree.

Control of boxelder bugs is not easy. The best way to control them is before they get inside the home. One insecticide that is most effective is chlorpyrifos as a liquid. It can be found in hardware stores, garden stores, and similar stores that sell insecticides. Read all label directions very carefully before purchasing insecticides and again before using.

An alternative to insecticides is the use of a soap mixture. Mix approximately 1/2 cup of a laundry detergent in one gallon of water in a hand sprayer or squirt bottle. Test the mixture first on an isolated spot before applying it to the entire area, as it may stain cedar or other siding. Spray the mixture directly on the bugs as often as necessary. The soap mixture affects only those boxelder bugs that are sprayed. It does not prevent other bugs from coming to the site. So it is important to spray the bugs as often as they cluster outside the building to maximize control.

The intent of boxelder bug control is to prevent them from entering indoors. Caulk or seal cracks and spaces found around the foundation, siding, windows, doors, and other entry points. If they are found inside, a vacuum is the best physical means. If large numbers are present, their numbers can be reduced with an aerosol ready-to-use insecticide containing either pyrethrins or tetramethrin. These sprays will not prevent more boxelder bugs from returning.

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VOICE MAIL: You can leave a question for a volunteer Master Gardener at 651-674-4417. Depending on the volume of calls, they try to respond within a couple of days. During office hours ask for the Master Gardener voicemail, after hours, select ext. 18. You can also get your question answered on the web at: www.extension.umn. edu/askmg.

The Chisago County Extension Office will be moving sometime in early December. Stay tuned to this column or check our website for more information as plans are firmed up. www.extension.umn. edu/county/chisago/mg/.

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