Feature

Why Do Invasive Species Like the Northeast?

Jane Hodgins
Northern Research Station, USDA Forest Service
April 10th, 2020 at 11:30AM
A male spotted lanternfly sitting on a maple twig.
A male spotted lanternfly sitting on a maple twig. Forest Service photo/ Melody Keena

An estimated 450 non-native forest insects have found their way to the US. Not all of these insects have caused visible damage to forests, but a handful of them, the proverbial poster pests like emerald ash borer, have significantly changed the surrounding landscape.

Research by USDA Forest Service scientists and partners explored the distribution of these insects across the nation and determined that a particularly large number of non-native forest insects have established in the northeastern region. The question researchers were left with is just why the Northeast has been ground zero for so many species of nonnative insects. 

A male emerald ash borer rests on a twig. Forest Service photo/Debbie Miller
A male emerald ash borer rests on a twig. Forest Service photo/Debbie Miller

The short answer to that question, according to Research Entomologist Andrew “Sandy” Liebhold of the Northern Research Station, a co-author of that study, is that research is not yet offering a definite reason. The longer answer is that beginning with the Pilgrims landing at Plymouth Rock, a combination of trade, transportation and the diversity of the region’s forests likely contributed to enabling forest pest invasions.

“Forest in the Northeast include many tree species, and that diversity serves up a multitude of host species that meet the feeding, breeding and overwintering needs of a wide range of forest pests,” Liebhold said. “On the other hand, forest diversity also protects forests; a single pest is less likely to cause massive mortality than you see in the West, where a single species really dominates a forest.”

A female Asian longhorned beetle lays an egg under the bark of a Norway maple bolt. Forest Service photo/Melody Keena
A female Asian longhorned beetle lays an egg under the bark of a Norway maple bolt. Forest Service photo/Melody Keena

Liebhold is one of several Northern Research Station scientists who contribute their perspective on invasive forest pests in the first season of Forestcast, a new podcast developed by the Northern Research Station. Titled “Balance and Barrier,” Season 1 offers a six-part series on the slow explosion of insect invasion in the region extending from Maine to Minnesota and from Missouri to Maryland. The series introduces the concept and consequences of biological invasion with a look at four poster pests: the emerald ash borer, gypsy moth, hemlock woolly adelgid and the Asian longhorned beetle.

The U.S. Department of Agriculture’s “Invasive Plant Pest and Disease Awareness Month” is a perfect time to check out the podcast and hear about some of the Northern region’s most destructive forest invaders: https://www.nrs.fs.fed.us/podcast/1/

https://www.fs.usda.gov/features/why-do-invasive-species-northeast