Checking trees for the latest threatening pest

The Upper Peninsula and northern Wisconsin already has endured the onslaught of spruce budworm and the recently arrived and still spreading emerald ash borer.

With August being national Tree Check Month, state and federal officials now advise to be on the lookout for the next potentially nasty bug — and this one targets our beloved maples, the bearer of one of the signature flavors of Michigan and Wisconsin woodlands.

The Michigan departments of Agriculture and Rural Development, Environmental Quality and Natural Resources are asking that people take “just 10 minutes” to check trees around their homes for a new invasive pest known as the Asian longhorned beetle.

As the name implies, the beetle is not native to North America, which is part of the problem — our maples have no time to develop any kind of defense against it and our continent has none of the natural parasites or other agents to keep the insect in check.

So, what should residents look for to tell if their trees are under attack?

Adult Asian longhorned beetles are distinctively large, ranging from three-quarters of an inch to 1 1/2 inches in length, not including their long antennae. The beetles are shiny black, with random white blotches or spots, and their antennae have alternating black and white segments. They have six legs that can be black or partly blue, with blue coloration sometimes extending to their feet.

The beetle first surfaced in the United States in 1996, probably carried here in wood packing materials. Neither Michigan nor Wisconsin has yet to confirm the Asian longhorned beetle, but it’s been found as close as Chicago — home to a number of summertime visitors to the North Woods — plus parts of Ohio, New York, Massachusetts, New Jersey and Toronto, Ontario, in Canada.

Like the emerald ash borer, a Eurasian species, it potentially can be carried in firewood, state officials warn.

“When traveling, leave your firewood at home,” said John Bedford, Pest Response Program specialist at the Michigan Department of Agriculture and Rural Development. “Buy it at your destination point and burn it there.”

But unlike the emerald ash borer, the Asian longhorned beetle is less picky about what it feasts on, state officials said.

Yes, it prefers maple, but also will infest birch, elm, willow, buckeye, horse chestnut and other hardwoods. Trees hit by Asian longhorned beetle must be destroyed to prevent the insect from spreading.

So why check now? Because adult beetles are active in late summer to early fall. Female beetles chew depressions in tree trunks and branches to lay eggs. When larvae hatch, they burrow deep into the heartwood of the tree, creating large chambers in the wood. The next summer, fully formed adult beetles emerge from trees by boring perfectly round, 3/8ths-inch-diameter exit holes. Sometimes a material resembling wood shavings can be seen at or below these holes or coming from cracks in an infested tree’s bark, state experts says.

This Asian invader does look similar to several native beetles such as the white spotted pine sawyer, the cottonwood borer and the northeastern pine sawyer, so it helps to get some education on how to tell them apart.

Anyone observing what they believe might be an Asian longhorned beetle or a tree that appears damaged by it should report it. If possible, capture the beetle in a jar, take photos, record the location, and report it as soon as possible to the U.S. Department of Agriculture at www.asianlonghornedbeetle.com or contact MDARD at 800-292-3939 or MDA-info@michigan.gov.

More information can be found on Asian longhorned beetles, including photos, on the Michigan Invasive Species website at www.michigan.gov/invasives, then going to “species profiles” on the left side of the screen and then “insects.”

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