Invasive insects: the Asian Long-horned Beetle

The Asian Long-horned beetle is an exotic insect that could cause great damage to Michigan forests and economy. Yet, it’s just one in a long line of exotics pests and diseases that have serious effects.

It’s not in Michigan and we don’t want to see it here, but we need to keep an eye out for this invader: the Asian Long-horned Beetle (ALHB), which can be a monster in the forest. Although it’s a gorgeous beetle of impressive size and coloration, its effect can be monstrous.

The ALHB prefers to feed in maples. Maples comprise more than a quarter of Michigan’s timber volume, and substantially more in the Upper Peninsula. This beetle can kill several other tree species as well.

The adult ALHB can be more than an inch long. They’re mostly jet black with flashy white splotches on their backs. The antennae are longer than their body and the segments of the antennae are alternately black and white. The antennae look like they have white stripes. Lots of information on ALHB is available on the Internet, including great pictures of all the life stages and the kinds of damage they cause to trees.

If you think that you see one, contact someone! Try a Michigan State University Extension office, a conservation district, the Department of Natural Resources or the Michigan Department of Agriculture and Rural Development. They would rather have a hundred false alarms than risk missing a positive identification.

A population of ALHB can be eradicated. Several have already been eradicated including those in Chicago, Toronto and an area of New Jersey. Success stories exist. The trick is to catch it as soon as it arrives; before it spreads too far.The forests need thousands of eyes.

Besides seeing the beetle itself, the adult exit holes when the adult beetles emerge from trees are pretty reliable evidence. The exit holes look as if someone drilled into the tree with a large bit. You can stick a pencil an inch or more into the tree. The ALHB is a wood borer, meaning the larvae eat their way through the wood of a tree. We also have native wood borers, such as the pine sawyer and white spotted sawyer. These are marvelous beetles that rarely cause damage to live trees. However, they can be spooky-looking to some people.

The ALHB tunnels are different from those of another exotic nemesis, the emerald ash borer (EAB), which is killing millions of ash trees in many parts of Michigan. The EAB tunnels are under the bark of ash trees. ALHB tunnels run deep into the wood. Their tunnels can weaken large branches or the tops of trees, which sometimes break off.

Any time a tree suddenly dies, suspicion is warranted. When more trees die suddenly and something seems to be spreading, then it should be reported. Of course, there are explanations that don’t involve exotic invaders. And, every tree eventually dies of something. However, a rapid succession from apparent health to evident death is a bit unusual. When additional trees follow the same pattern, an alarm should be raised.

Exotic pests have already taken a toll in North American forests. Chestnut blight has all but eliminated the once most common tree in the east. Many of the Conestoga wagons were reportedly made from chestnut. Dutch elm disease has left a huge hole in our eastern forests and an even larger footprint in our residential areas. You now have to be over 50 years old to remember the graceful elm-lined streets and boulevards of many cities and villages.

Commercial production of the historic powerhouse eastern white pine is hamstrung by a blister rust. Butternut is on its way out from a canker. Many large beech trees, especially in the Upper Peninsula, are dying from beech bark disease. Ashes are dying in areas around much of the state. Oak wilt is raging through many of our oak woodlands.

Over half of Michigan’s forest volume has been affected or is at risk of serious damage from exotic pests. Losses involve more than just losing trees – these pests are serious issues for our economy, environment and sense of place. Costs of damage and control rack up into the billions. What might seem “natural” might not be natural at all.

What can you do? Watch your trees. Learn about these threats. Talk to your neighbors. Stop moving firewood around. If you’re a forest owner, manage the woodlands for health, vigor and diversity. The forest is a whole lot more than just a pretty place to play.

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