At the end of the street on which I grew up, there was a substantial bit of forest. "The woods," we called it. It was a perfect place to be a kid with an active imagination. There was a brook running through it, and there even were paths already in place because the Great Worcester Tornado had cut them in 1953, six months before I was born. When I came back from my first year in college, the woods were gone, replaced by a housing development that had used the old paths as a blueprint for new streets.
Anyway, this developed in me a great love for forests. I even worked for three summers in a state forest down by the Rhode Island line. Consequently, I was sorry that all the thunder about the midterms caused me to miss this great piece by Catrin Einhorn in The New York Times about the perilous state of America's forests due to their infestation by various invasive insects.
Epidemics are escalating, across numerous species, as more and more pests and pathogens invade forests. Their entryway is global trade—in live plants, and in the countless products that are shipped in wooden pallets, crates and other packaging. As trade has boomed, so have the opportunities for tiny stowaways to wreak havoc. “We’re moving insects and microbes around the world through trade very rapidly, and basically running an experiment” to see which ones will take hold, said Bernard Slippers, a forest pathologist at the University of Pretoria in South Africa.
The attackers have killed billions of trees already, with countless more under threat. In some severe cases, forests are transforming into bleak spaces of brambles and vines.And the impact extends far beyond the woods. Trees filter water, stabilize the land and clean the air. They absorb and store planet-warming carbon dioxide, fighting climate change. They create the three-dimensional habitat that countless species use for shelter and shade. And they offer something even more foundational.
And these plagues are right here down the street, by the Charles.
While tree species are getting hit all over the world, the northeastern United States has emerged as an epicenter. Scientists attribute that to both the volume of imports and the rich variety of tree species in the region. The beetle responsible for some of the worst recent damage is tiny, bright green and shimmers like a jewel: the emerald ash borer. Scientists don’t know exactly when it entered the United States, but by 2002 in the Detroit area, something was terribly wrong with the ash trees. Their crowns died back and their outer bark split apart, revealing strange, serpentine marks underneath. The bright green beetles were found among dying trees. Less than two decades later, the borer had so devastated North American ash trees that all six of the most prominent species were classified as endangered or critically endangered. Death rates for mature trees are sky high.
The woolly adelgid is killing the hemlocks. A Japanese microorganism is killing the beeches. We've already lost the elms and the chestnuts to invasive diseases. By the way, the ash trees moved in to replace the elms and now the ash trees are being attacked.
The number of highly destructive pests identified by scientists has increased since 1990, as global trade ramped up, said Juliann Aukema, a scientist who helped identify the surge and is now an assistant director of research at the Forest Service. The direct costs are formidable. In 2011, researchers estimated that bark- and wood-boring insects would cost local governments in the United States around $1.7 billion a year in tree removal, replacement and treatment.
One way scientists are fighting the infestations is with ... other insects. As Einhorn points out, the scientists are aware of the irony.
With oversight from the federal government, several universities and state agencies are trying to fight hemlock woolly adelgid with what’s known as biocontrol, bringing in predators to drive down their numbers. Cornell has released hundreds of thousands of flies and beetles in recent years. But scientific protocols have tightened over the years, and many scientists think insect predators could give embattled tree species a chance. Four species of stingless wasps from Asia have been enlisted to fight emerald ash borer, and an imported fungus has helped tamp down the spongy moth, which defoliates oaks and other hardwood trees.
It's a crisis, and it's all bugs on deck.