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Coming soon to a woods near you

A lot of attention is being given to aquatic invasives this year. This makes it easy to forget about terrestrial invasives, both insects and plants that threaten the quality of our northwoods environment.

While there are many plants and insects that are not native and pose a great threat to our environment, three are insects that are easy to recognize and have the potential to cause great loss of trees in northern Minnesota.

The first is the emerald ash borer. First found in Michigan, it spread rapidly to Minnesota and was first detected in 2009. The nearest detected locations are the northern suburbs of Minneapolis-St. Paul and Superior, Wis. In areas where the emerald ash borer has become established, virtually all ash trees have died or been removed. The most common route the beetle takes is to hitchhike on ash firewood. Moving firewood out of local areas is illegal.

The emerald ash borer is a small, emerald green beetle. The color is what distinguishes it from others. There are several other green beetles so a picture helps with identification. It is unlikely that you will see the beetles since they infest the tops of ash trees first; the first sign of an infestation will be the tops of the trees dying.

Second is the gypsy moth. Gypsy moths are from Europe and damage trees by defoliation. We have had forest tent caterpillar infestations in northern Minnesota for many years with infestations that occasionally defoliate trees but then are not seen for years afterward. Gypsy moths, on the other hand, can completely defoliate an area, leading to the death of trees. Aspen and oak are their favorite meals.

The male and female gypsy moths are very different. The female is larger, up to a two-inch wingspan, is white with bands of black while the male is browner and smaller. Pockets of gypsy moth have been identified and eradicated along the North Shore of Lake Superior. The female lays an egg mass in many places, including camping equipment, making their spread more rapidly.

Third is the Asian long-horned beetle. First found as a hitchhiker in wood packing boxes in New York, this beetle has spread to Illinois, destroying millions of trees in its path. In Minnesota, we see a white-spotted sawyer which looks a lot like the Asian long-horned beetle but is not nearly so destructive. The beetle is 1 to 1.5 inches in length, is glossy black with irregular white spots and has antennae that are as long as the body. There's an easy way to tell the difference; the native beetle has a white spot behind the head.

Identifying these pests so that action can be taken to slow or stop their spread is of vital importance. Minnesota has a joint program between the Minnesota Department of Agriculture, Department of Natural Resources and the University of Minnesota Extension to identify infestations of these pests. The program relies on the public to report suspected infestations. Volunteer Forest Pest First Detectors assist these agencies by photographing, collecting and forwarding information to a central site. The website is and the hotline is (888) 545-6684 to report a suspected infestation.

Reference the University Of Minnesota Extension Service website,, for more information on horticultural topics. In addition, local Master Gardeners will again answer your questions on home horticulture. Call (218) 444-7916, leave your name, number and question and you will receive a return call.