Gypsy Moths and National Parks - Not a Good Mix

Karla Salp
Pest Program Outreach Coordinator

Male gypsy moth on branch

On my recent visit to the East Coast to view gypsy moth damage, I realized upon picking up my rental car that taking the brand new Jeep down the best roads to see gypsy moth defoliation could be costly for the State of Washington.

Luckily, I met Dr. Bob Cook – a biologist with the National Park Service on the Cape Cod National Seashore – who had a beat up Ford pickup perfect for going down the roads less traveled.

Roads Less Traveled 

The roads we drove were primarily dirt and maintained by the occasional car driving down them, as evidenced by the not-infrequent fingernail-on-chalkboard branches scraping the side of the pickup and the occasional “tree branch tunnel” through which we passed.

Driving along Highway 6 on my way to meet Bob earlier, it had seemed as though everything was defoliated; I could even see male gypsy moths fluttering near the trees as I drove. However, as we made our way through the lonely roads, we noted that some of the oak trees in the National Park were lucky enough to escape damage.

Soon enough, though, we discovered sites of complete defoliation. It was awe-inspiring to see the sun streaming unhindered through the naked forest, knowing these trees should have been lush, green, and shady at the end of July.


Gypsy Moths Are Smart

We continued to make our way from hollow to ridge (a difference of a mere few hundred feet) as we wove in and out of various levels of defoliation. Where the forest was totally leafless, moths and egg masses were scarce. But upon returning to areas that had only been partially defoliated, moths were fluttering everywhere and egg masses began appearing again on the trees.

The gypsy moths were no fools. They were defoliating entire acres of forest and then moving to new, healthier forests to lay their eggs, enabling the young to hatch out next spring in a stronger, healthier forest.

Oak trees starting put leaves back on at the end of July

Gypsy Moths and the Tourism Problem

Touring the park, I couldn’t help but think of the 15 national parks in Washington that together receive more than 7.6 million visitors a year.

Like our parks, the Cape Cod National Seashore also receives thousands of tourists each year. But tourism in the area had been dampened by the outbreak owing to the nuisance caused by the moths making camping a nightmare.

I saw reports on social media of tents being covered with male moths and even someone who had a female lay eggs in their sleeping bag!

This is the second year of defoliation in the area, which is a major stress for the trees. It could be enough that some of the trees may die. If they are defoliated again next year, entire sections of the forests in the National Park could die. 

Heading back to the National Park headquarters, I reflected with gratitude that our own national parks are safe from the gypsy moth, though it will take continued diligence to protect our forests.