Peril of the Pest
Asian longhorned beetle poses serious threat to trees
It's called an invasive pest, but really the word "pest" doesn't do justice to the Asian longhorned beetle (ALB). This insect is far more than a nuisance; it has the potential to completely devastate tree populations. That's why municipalities, state and federal agencies and landowners across the Northeast are seriously concerned about its spread. The ALB has already appeared in some areas of this region, notably in Worcester, Mass. There, a massive effort continues to contain and eradicate the ALB. In other areas, work is being done to scout for and prepare for its arrival.
The experience in Worcester is important for all those in the Northeast to hear. It began in 2008 when a resident discovered a large beetle and reported it to the USDA. The beetle was quickly confirmed as the ALB, and since that time more than 31,000 trees have been removed in Worcester because of the infestation.
Currently, a 110-square-mile area in and around Worcester is under quarantine. There, the search is on for any tree infested by ALB. It's a massive effort that includes street trees as well as trees in parks, on private property and in wooded settings. Typically, a ground search is done first, and if suspicious activity is spotted, climbers are brought in to go up in the trees. Those trees found to be infested are marked with a red band of paint and removed. The removals must be done by contractors who have been specially trained and certified by the Massachusetts ALB Cooperative Eradication Program. The debris must be chipped to USDA specifications, with chips small enough that no pest could survive.
In the last four years, an astounding 2.4 million trees have been surveyed in the greater Worcester area, "and they're not done yet," says Jennifer Forman Orth, state plant pest survey coordinator at the Massachusetts Department of Agricultural Resources. With so many trees to scout just within the Worcester area, it's no wonder every effort is being made to prevent the spread of the ALB to other communities or the open forest. Forman Orth devotes much of her efforts to outreach, educating the public about the ALB (as well as other pests) and letting them know what they can do to help prevent its spread.
The first thing to know is that the beetle itself isn't often seen. Even within the heavily infested area of Worcester, only about 1,000 adult beetles were collected the first year after the infestation was confirmed; the year after that, about 100 beetles were found. Last year only around 30 beetles were collected. What's easier to spot is the damage the beetles do to trees. "There are perfectly round, smooth-edged exit holes [that] are a little bit smaller than a dime in diameter. You can also see egg-laying sites, which are up to a half-inch in diameter and look like when someone takes a bite out of an apple," explains Forman Orth. "You can also look for frass, which is basically the beetle's waste material and looks a lot like sawdust because they are eating wood."
To better scout for damage, it helps to understand the life cycle of this pest. "A lot of people don't understand that the major damage being done by the ALB is being done when it's in the larval stage," says Forman Orth. "It's all being done inside the tree, so it's basically damaging the tree from the inside out." The process begins when the adult beetles emerge from the trees beginning in July and August. "It will mate and start to chew holes in the bark to lay eggs. It makes these little pits, eating through the bark to the cambium layer, and lays eggs in each of those pits," she explains. "The eggs hatch after about two weeks and larvae start boring their way into the tree. They can be in that stage of their life, getting larger and larger, for either one or two seasons." Depending on the diameter of the tree, the larvae can bore all the way to the center of the tree before working their way back out again. At that point, they convert to the pupal state before boring their way out of the tree - and leaving the perfectly round exit hole - as adult beetles, at which time the process begins anew.
The primary host tree of the ALB is maple, says Forman Orth. Birch, elm, ash, poplar, willow and horse chestnut can also be attacked. "It doesn't attack coniferous species, and one hardwood host not on the list is oak," she notes.
Most of the activity from this pest occurs in the upper canopy of trees, which makes detection all the more difficult. Forman Orth says that even the highly trained surveyors in the Worcester area can miss infested trees. "If you do a ground survey - standing on the ground with a pair of binoculars checking a tree - you're only about 60 percent likely to find an infestation the first time you pass through," she explains. So trees must be checked multiple times. For woodlot owners, she recommends making surveys part of an annual or biannual walk through the woods. For best visibility, the ideal time to do this is when there are no leaves on the trees.
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"Awareness is up, but more outreach needs to be done. It's not just about the beetle, it's about recognizing tree damage and recognizing that you should report if you see something suspicious," emphasizes Forman Orth. "You know your property better than anybody. You know when something weird is going on or if there's suddenly a lot of tree damage."
Anyone who sees what they believe may be an Asian longhorned beetle or related damage should report it to their state department of forestry or agriculture (see sidebar for some reporting options). There are many look-alike species - perhaps the most common case of mistaken identity occurs with the whitespotted sawyer - but if there's any question, a report should be made. "I'd rather get 10,000 false reports than have someone not call in an actual infestation," says Forman Orth.
Early detection of an infestation is critical. "The main reason the infestation is as large as it is is because the beetle remained unreported for more than a decade," Forman Orth explains. That's why more than 30,000 trees had to be removed, and the infestation is still not under control. The ALB was also found in the Boston area in 2010. There the infestation was believed to be only a couple of years in the making and just six trees had to be removed. "You absolutely want to get it early, and that's why reporting is so important," she emphasizes.
Caitlin Cusack, community forestry outreach coordinator with UVM Extension, heads up a similar program in Vermont called Forest Pest First Detectors (www.vtinvasives.org/tree-pests/first- detectors/program), which trains community volunteers to not only scout for but also educate the public on invasive pests such as the ALB and emerald ash borer. "In a lot of cases where invasive pests have been discovered, it's been by citizens," says Cusack.
More than 31,000 trees have been removed in Worcester, Mass., since 2008, when the ALB was first detected. The effort has cost millions of dollars, but the dangers of the infestation spreading are far greater.
That was the case with the Worcester ALB infestation, and Cusack recently organized a trip for First Detectors to visit Worcester to see firsthand the destruction caused by the ALB, and how the community, state and federal governments have responded. She's also studied the experience of communities in the Midwest that have had major invasive pest infestations of both the ALB and emerald ash borer. "The main lesson you learn is how important the local response is. Chicago had an amazingly quick response to an ALB infestation, where all levels from the federal government down to the local communities were working together," she explains. "The plan here in Vermont with the First Detectors program is not only to get more eyes and ears on the ground with our volunteers, but also to spread the word so that citizens throughout the state know what to look for. That way we have liaisons between the local communities and the state and federal government. And when these pests arrive, there already is communication going on."
The goal is also to encourage local communities to start planning and budgeting for an invasive pest infestation that might require trees along streets and in parks to be removed and replaced.
Besides scouting for pests like the ALB, one of the most important things everyone can do to help prevent its spread is avoid moving wood long distances. "We encourage people to buy and burn wood locally and to use kiln-dried wood if they need an outside source," says Forman Orth. That means not transporting wood on camping trips or to vacation homes, as well as buying home heating firewood from local, trusted sources.
It was the moving of wood, after all, that brought the ALB to the U.S. in the first place. "We know that [the] ALB came to North America through infested solid wood packing material - crates and pallets that are used to ship goods here from Asia," explains Forman Orth. It's uncertain how the pest came into Worcester, but there is a significant manufacturing presence in the city. "There seems to be a greater risk in urban areas where there is an industrial component and also a forest," she explains. "You would need to have the hardwood host trees as well as the pathway in."
University of Massachusetts Associate Professor Charles Schweik developed the Outsmart Invasive Species smartphone app (available for download on the iTunes site), which allows landowners to snap a photo of suspected invasive pests and send it, complete with GPS coordinates, to a database where researchers can review the photo to determine if action is required.
Now that it's here, this invasive pest is proving difficult and expensive to control. Removing and destroying infested trees is currently the only really effective response. "Research is ongoing to try to find alternate solutions, but as of now, once ALB infests a tree, there is no way to cure the tree," says Forman Orth. Part of the reason is that the ALB is a wood-boring insect. It bores right through the bark of the tree all the way into the heartwood, past the tree's conductive system. "So any kind of systemic pesticide you're choosing to apply to the tree isn't going to be effective if there's already ALB larvae inside," she explains.
For woodlot owners, preventatively treating a forest full of trees is unlikely to be a viable option, so vigilance remains the best bet in preventing major infestations that impact forests in the Northeast. Woodlot owners in general and, given the ALB's preference for maple species, maple sugar producers in particular have been a key part of education efforts. "The maple sugar industry is extremely concerned about this, not only in Massachusetts, but in Vermont and the other states," says Forman Orth. "They've been extremely proactive in asking us to come out for trainings and getting updates." Wood products groups have also been involved with trainings, and these organizations have helped spread the word to the public about the ALB.
Forman Orth worries that some people might be suffering from "apocalypse fatigue" in continually hearing the message. "But we really need to keep making them aware of ALB," she stresses. "I want people to recognize ALB the same way they recognize a dandelion in their lawn. You need to know how to recognize the insect and know to report it."
Patrick White is a freelance writer based in Middlesex, Vt. Over the past 10 years, he has covered a wide range of agricultural operations around the Northeast. He is always on the lookout for unusual stories.