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Asian Beetles and Boxelder Bugs, Your Unwanted Visitors

Jeff Hahn, Department of Entomology, University of Minnesota

University of Minnesota Extension, Stearns County News
September 9, 2015

Source:  Beth Berlin, Extension Educator-Horticulture
University of Minnesota Extension
Stearns, Benton & Morrison Counties

Asian Beetles and Boxelder Bugs, Your Unwanted Visitors
By Beth Berlin, University of Minnesota Extension

ST. CLOUD, Minn. (09/09/15) —  Fall to many is a beautiful time of year, the number of mosquitos and gnats decrease, however homeowners find unwanted bugs in or around their home.  Common unwanted guest that congregates in and around the home are the Asian beetles and boxelder bugs. The Asian beetles are the multi-colored beetles often mistakenly called lady bugs.  Both of these insects are seeking out a site to overwinter, and unfortunately many of them find their way into the home. These home invaders do not feed or reproduce in the home, but are definitely an annoyance.

Boxelder bugs are easily identified by their black and deep orange/bright red colors; their wings lay flat on their bodies. The adult boxelder bugs are capable of flying several blocks and sometimes may even fly further than that. The boxelder bugs like sunny areas and are attracted to buildings with a lot of southern exposure.  As weather cools, these insects will push into cracks and enter houses near the foundations.  Many crawl under shingles and get into wall voids and attics.  They also may enter through doors, windows, vent openings and other accessible areas.

The multi-colored Asian lady beetles have been a nuisance and annoyance for many years. Initially introduced to be a biological control of aphids, populations appear to be more concentrated near agricultural fields.  Unlike the common lady beetle, or ladybug, the multi-colored Asian lady beetles like to overwinter in large numbers in and around buildings.  Once inside the home the Asian beetle has the ability to emit a chemical to attract others, which can lead to hundreds if not thousands of unwanted visitors.  Sometimes their presence isn’t discovered until the following spring when temperatures begin to warm up, however entry occurred the previous fall.

Effective control begins outdoors.  Carefully inspect and then seal up any potential entry points with caulk, sealant, or screening. Both insects need only a very small opening to enter the home, so it is important to check all possible entry points and take the time to seal them up.

If populations are too great for your level of tolerance residual insecticide can be used.  Carefully read and follow all product directions before using around the exterior of the home.  Because the insects tend to like the warm, sunny conditions focus your efforts on the south and west sides of your home. The best time to spray is when you first observe the insects clustering around the outside of your home or other building before they begin finding entry points.  Effective insecticides that are available to the public include bifenthrin, cyfluthrin, cyhalothrin, deltramethrin, permethrin and tralomethrin.  There are many trade names for these chemicals, simply read the “Active Ingredients” on the label.

Another option to control boxelder bugs with some effect is using a soap mixture.  Mix 1/2 cup of a liquid laundry detergent with a gallon of water and place in a hand sprayer or squirt bottle.  It is important to test this mixture first on an inconspicuous spot before applying it to the entire area, this will ensure the product won’t stain or discolor your home.  Apply a coarse spray directly on the bugs as often as necessary.  It is important to note that the soap mixture affects only those boxelder bugs that are sprayed and does not prevent other bugs from returning to the site.  Soap mixtures are not effective in controlling multi-colored Asian lady beetles.

Unfortunately once these pests get inside, the only practical control is to remove them by hand or with a vacuum cleaner.   The use of insecticides indoors is not effective and is not recommended.


PHOTO: Multicolored Asian lady beetle by Jeff Hahn, Department of Entomology, University of Minnesota


Beth Berlin
Extension Educator, Horticulture
(320) 255-6169
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