The discovery of the emerald ash borer in St. Paul has not only gotten tree lovers concerned about their trees, it's also prompting bird lovers to worry about what the chemicals used to treat the trees might do to their favorite animals.
The standard treatment, Imidacloprid, has generated controversy in Europe because researchers found it changes the behavior of honeybees. It may not kill them, but it can interfere with the way they do their work. And honeybees are struggling to survive.
The chemical, sold under several brand names including Merit and Admire, is injected into the soil, and the tree absorbs it. Imidacloprid is a relative of nicotine, and it kills insects -- including the larvae of the emerald ash borer -- by disrupting their nervous systems.
Vera Krischik, an entomologist at the University of Minnesota, studies what Imidacloprid does to non-target insects.
Her research has focused on pollinating insects -- those that feed on pollen or nectar -- and she's found that Imidacloprid will kill some of those beneficial insects.
Krischik says Imidacloprid also kills bugs that eat leaves, such as Japanese beetles.
"Japanese beetle, which is usually considered very difficult to control, if it takes two bites it just sits there, and after a week they just kind of dissolve," she said.
So what about a bird that eats the Japanese beetle?
"My gut reaction is it's going to be minimal, because the beetle ate so little to die, that it's not through its whole body," she said.
Arborists are also applying a new chemical -- emamectin benzoate, sold under the name Tree-age -- on some trees in St. Paul. Early research in Michigan shows if trees are caught early enough, they can be protected. But there's been very little research on the chemicals' possible impacts on birds.
Syngenta manufactures Tree-age. Spokesman Steven Goldsmith says because it's injected into the tree, rather than sprayed on, it can be used at relatively low concentrations. So by the time it gets to the leaves, there's not enough of it to harm an insect that eats the leaves.
The chemical is aimed at the larvae that tunnel under the tree bark, but Goldsmith says even if a bird eats a dead larva, it should be OK.
"The amount of the product that would be within a larva, even if it was ingested by woodpecker, is small, so there would be no risk to that animal."