Eastern hemlocks

[Editor’s note: For more than 30 years, Faith Campbell has worked as an environmental advocate. She began specializing in invasive species in 1986 and has worked on forest health advocacy for The Nature Conservancy since 2004. Faith is excited to be featured on Cool Green Science to help educate you on what can be done to keep our trees and forests safe from invasive pests. Look for more posts from Faith in the future.]

It was with elm trees in mind that I began, twenty years ago, to study tree damage caused by non-native insects and diseases. Growing up in Arlington, VA, I loved the elm trees shading the District of Columbia streets, traffic circles and parks. They were tall, elegant, with limbs intertwining. And they were early to leaf, ushering in the start of spring.

But even then, the elms were disappearing, victims of Dutch elm disease. Streets that used to be lined with these beautiful trees were bare or had only small saplings. Heroic efforts were made to save the elms, but few of these majestic American icons are left now — only street names commemorating the once ubiquitous street tree.

Unfortunately, the elm wasn’t a unique story. By the 1990s, nearly 400 pests had been introduced and had killed many types of trees — among them, the European gypsy moth, chestnut blight, white pine blister rust and — yes — Dutch elm disease.

And new threats loomed, including proposals to import logs from Siberia to provide raw materials to wood processors in the Pacific Northwest.

Foresters and plant health scientists in academia, state agencies and the USDA Forest Service demanded caution. The USDA Animal and Plant Health Inspection Service (APHIS) convened a team staffed by USDA and outside scientists that prepared a lengthy pest risk assessment that evaluated the likelihood that a raft of insects and pathogens from Northeast Asia might be carried on those logs to the U.S.’ West Coast — and the damage they might do if they did come. As a result, APHIS adopted stringent regulations that have — for 20 years — deterred people from actually importing logs from Siberia.

Victory! But wait…

Since the mid-nineties we have learned about dozens of introductions of tree-killing insects and pathogens. These include the Asian longhorned beetle, emerald ash borer and sudden oak death pathogen.

How did they get here? In short, they hitchhiked into the country using other pathways: in the crates and pallets that hold imports, in plants we import to beautify our yards, even in trinkets and décor items.

My involvement with tree pests took over my life. Ask anyone who knows me — if I go into the woods, or see a pallet next to a building… I start to spout about the missing trees, the danger…

I think my obsession is natural — after all, just look at a partial list of the trees already severely reduced:

  • American chestnut throughout the East
  • American elm in our cities
  • Eastern hemlock in the Appalachians
  • High-elevation pine trees in the Western mountains
  • Dogwood in the Mid-Atlantic and North
  • American beech

And those facing imminent threats:

  • ash trees throughout the Midwest and East; later in the Plains states
  • maple trees
  • black walnut

We have our work cut out for us. But I’m inspired by the colleagues who have worked beside me over the years — as well as the new crop of experts working tirelessly to protect our trees from invasive insects and disease.

[Image: Eastern hemlocks. Image source: Nicholas_T/Flickr via a Creative Commons license]

If you believe in the work we’re doing, please lend a hand.


  1. All of our efforts to eradicate invasive-exotic plants and animal species will be for naught, unless we can educate the public about not importing them!

  2. Do not forget the pine bark beetle It is destroying pines in the south.

  3. Invasive species are devastating our forests. I backpack in the Smoky Mountains and where there once were thick stands of hemlock now there are only dead skeletons of trees. I still see the giant stumps of American Chesnut which was driven to extinction, and almost all of the large dogwoods in my town are dead now. I hike in Torreya State Park in Florida, named for the Torreya which is only found there, now all Torreyas are dead. Saplings grow from the stumps but die when they reach a few feet tall. The decimation of the American Chesnut has also resulted in the loss of a major food source for Black Bears in the Smokies. Work like that Faith Campbell is engaged in is vital if we are to save our native forests.


  5. GREAT.

  6. Keep fighting the good fight Faith!

  7. Can a integrated pest management program be used?

    i.e. (cartoon example) Like the cat, dog, … elephant … mouse. oops cat.
    I know it is a failed program nonetheless.

    Can a sequence in a sustainable system or ecological redress
    be made to control the beetles, etc. by using plants animals beneficial for control. {example} Are there a fast growing plants etc. to be sacrificed to be more attractive to the beetle and keep it off the elms transferring them out.

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