Slightly Better News on Boston’s Asian Longhorned Beetle Outbreak

After my last post a company called “Arborjet” tweeted Union Park Press to alert me to the ongoing insecticide injections meant to preserve Worcester-area trees from the ravenous Asian longhorned beetles (ALB).  The beetles are in the news because they were detected this week in Boston on the grounds of Faulkner Hospital–across the street from the Arnold Arboretum–and because they are evil. (Well, they’re really just another form of life struggling to survive, but they survive by killing trees I like; thus, EVIL. Gardeners tend toward moral absolutism.)  According to the Boston Herald, there are 100,000 trees within the beetle’s one-mile flying radius from the Faulkner site… for now. But no more beetles have been detected yet, which is slightly better news.

But back to the injections!  This spring, the USDA started having trees it considered at risk for ALB infestation around Worcester injected with imidacloprid, an insecticide that attacks insects’ nervous systems. The chemical spreads throughout the tree, from root to tree-top, and any insect that tries to eat any part of the tree will be poisoned.  There have been charges that imidacloprid harms bees; Germany has banned its use in some seed treatments due to concerns about bees. If you’re truly curious about this stuff, you can read the USDA’s comments on imidacloprid, ALBs, and bees in this pdf. In short; it’s used in a lot of other places, it seems to be safe, there isn’t much evidence that it’s killing bees, and the USDA is still studying exactly what injecting it in trees will do to bees.

That said, injecting trees with insecticide is not a very good way to preserve Boston’s parks or New England’s forests. It’s expensive, and it has to be done on the ground–you can’t just spread it by flying a plane over Stony Brook Reservation, even if you wanted to kill every bug in the place and destroy the local ecosystem. Private arborists charge more than a hundred dollars per tree for injections in mature trees, and you have to get to *every* host tree in the area to be effective (or the beetles will simply take refuge there). It’s not clear to me how long the imidacloprid persis in trees, or if these treatments will have to be repeated next year, or the year after that, or the year after that… So far, Massachusetts and the USDA have already spent more than $50 million to get rid of the ALB, according to this press release by the Massachusetts Department of Conservation and Recreation.

Apart from the expense, imidacloprid doesn’t just kill ALBs. It’s injected both into the tree and into the soil around the tree, and it destroys any insect that eats plants–including all those native caterpillars that form the basis of our native food chain, as Doug Tallamy told us in Bringing Nature Home. I understand that we need to sacrifice some life to preserve our current ecosystem from this wretched beetle, but it *is* a sacrifice. We just don’t have many places left where our local bugs can live.

Even more tragically, the injection can’t save trees that are already infested. To quote the USDA Asian longhorned beetle control fact sheet, “Control treatments are not effective in killing all of the beetles that may be in a tree already infested with ALB.” That makes sense. Imidacloprid only works if an insect ingests it–and beetles spend a fair amount of time not eating when they are eggs and pupae. Leave the tree, and you’re leaving a launching pad for the next ALB infestation.

So there’s a treatment that works, but not on infested trees, and it’s expensive, labor-intensive, and harms the local ecosystem, and may have to be repeated. That’s slightly better news than before. Slightly.

A community meeting about the beetles is scheduled for Tuesday, July 13, from 6-8 p.m. in the Franklin Park Clubhouse on Circuit Drive in Franklin Park.

Photo courtesy of Massachusetts Department of Agricultural Resources (Photographer: Jennifer Forman Orth)

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