Michigan on the lookout for tree-eating Asian longhorned beetle
Imagine a Michigan without maple trees.
Impossible? Not if the Asian longhorned beetle moves in from neighboring Ohio, where the invasive insect has already infested more than 18,000 trees. Nationwide, the voracious beetle has resulted in the destruction of 80,000 trees.
“More than 1 billion maple trees grow in Michigan, so the potential devastation here is mind-boggling,” said Joanne Foreman of the Michigan Department of Natural Resources (DNR). “Once the Asian longhorned beetle infests a tree, you cannot save the tree. That’s why preventing its spread is critical.”
The Asian longhorned beetle (ALB) is considered a major threat because it feeds on a variety of hardwood trees including birch, poplar, willow, sycamore and horse chestnut. But maple trees are its favorite.
“Because 12 species of trees in Michigan are at risk if ALB were to arrive here, the prognosis may be even worse than what we saw with emerald ash borer,” said John Bedford, pest response program specialist for the Michigan Department of Agriculture and Rural Development (MDARD).
Emerald ash borer, which is another invasive insect, has killed tens of millions of ash trees over the past 15 years in Michigan.
Scientists believe that like the emerald ash borer, the ALB arrived in the United States from Asia, probably through infested wood-packing materials. Today, the ALB is found in parts of southwest Ohio, Massachusetts, and New York, as well as Canada and Europe.
Since its U.S. arrival in 1996, ALB has caused significant economic and ecological damage.
Adult female beetles chew up to 90 oval depressions into the bark of the host tree and lay a single egg beneath the bark at each site. As the eggs hatch, the larvae tunnel under the tree bark unseen all winter and eventually chew into the woody tree tissue. In the warmer months, adult beetles chew their way out of the tree, leaving ¼ inch or larger perfectly round exit holes.
“They choke out the tree by disrupting its circulatory system, where it gets all its nutrients,” said Jonathan Shields, of the Ohio Department of Agriculture and a participant in the Asian Longhorned Beetle Eradication Program. “Then the larva bores through the heartwood and damages the tree’s structure.”
Once the beetles have inflicted this Swiss cheese–like damage, branches begin dropping and the tree dies within 10 to 15 years.
Unwelcome guest in the Buckeye State
Adult beetles are 1 to 1½ inches in length with six legs. Their shiny black bodies have random white spots, and their antennae are banded in black and white. Although the beetles often remain hidden, they leave destruction in their wake: exit holes about ¼ to ½ inch in diameter, sawdust-like material around the tree, dead branches and, eventually, dead trees.
There are two native beetles that are easily mistaken for the Asian Longhorned Beetle, the white spotted pine sawyer and the cottonwood borer. Learn how to identify each species.
In Ohio, the beetle was first reported in the summer of 2011. Having seen the damage already done in Massachusetts and New York, the Buckeye State quickly created the Asian Longhorned Beetle Eradication Program to fight its spread.
“This insect creates enough of a potential risk to agriculture, to a number of different industries, and to the general way of life that the federal government has determined it’s worth the investment to eliminate it and protect the trees in southwest Ohio,” Shields said.
“Unchecked, it would spread throughout the U.S.”
The U.S. and Ohio Departments of Agriculture have quarantined 61 square miles east of Cincinnati in an attempt to contain the ALB, which has already infested 18,783 trees and prompted the removal of nearly all of them. The quarantine abuts a large state park and wilderness area.
Once an infested tree is identified, it is cut down and chipped. The larvae are killed in the process, Shields said.
No one is allowed to move trees, branches, stumps or firewood from any hardwood species out of the quarantined zone.
“If there’s a take-home message it is and always has been that you should buy firewood where you’re going to burn it and not transport it,” Shields said.
Michigan ready with plan of attack
Michigan’s success with eradication of ALB, should it arrive here, hinges heavily on early detection. The state is in the midst of a campaign to educate the public about the damage caused by invasive species such as the ALB.
All Michiganders – landscapers, tree nurseries, arborists, homeowners and outdoor enthusiasts – are asked to pay attention to trees, especially maples, and look for dying branches, exit holes in large branches or trunks, and any other signs and symptoms of infestation and to report anything suspicious.
“Almost all ALB in the United States have been found by someone in the public who knew what to look for, who saw a big ugly black bug on their car or in their truck bed, and they reported it. So we know outreach works when we engage the public,” said Susan Tangora, of the DNR forest resources division.
Federal, state and local officials are already prepared to begin a survey and eradication effort, including removing and destroying infested trees, in the event that an ALB infestation is found in Michigan.
“We are doing as much pre-planning as we can in Michigan so if the ALB arrives, we will be ready,” Bedford said.
Tangora said Michigan park rangers are trained to survey incoming vehicles and parks in search of ALB or other invasives. Biologists also set pest traps and conduct aerial surveys in search of tree damage.
Federal, state, regional and local officials take the ALB – and its potential devastation – very seriously.
“We treasure our trees in Michigan. So it’s up to all of us to be on the lookout for invasives like the Asian longhorned beetle and report any sightings immediately. Our quality of life depends on it,” said Joanne.
This article is part of the “Not in My Backyard” series, which is aimed to raise awareness of invasive species’ impacts in Michigan. To learn more about the Asian longhorned beetle and other invasive species, including ways you can help in this effort, visit Michigan.gov/NotInMyBackyard.