Scott said there are 10 species of pine sawflies in Washington County, including the European sawfly that Cline encountered.
Cline got lucky.
He was able to get rid of the pests quickly enough that his trees weren't severely damaged.
Favorable weather conditions allowed the pine needles to grow back quickly, leaving him with only 25 trees he will have to postpone selling until next year when they've had more time to recover.
That's not bad for a population of 2,000 white pines among 30,000 trees, Cline said.
The key was treating the trees quickly, he said.
Because he walks his farm just about every day, Cline caught the European sawfly early and began spraying the insecticide Orthene immediately, finishing within three days.
Cline said he prefers a more organic approach - squashing bugs on his trees.
"This year you couldn't squash them because there's just too many of them," Cline said.
The larvae is called a sawfly because the appendage that the adult wasp-like female uses to lay eggs in leaves and plant stems looks like saw teeth, Scott said.
If the sawflies aren't caught before they get to the pine needle bud, next year's bud is lost, Scott said.
Local residents should look for the larvae on the tips of pine needle branches, Maryland extension agents said.
Bob Bishop, horticulturist for Frederick County's Cooperative Extension Service, said he wouldn't worry as much about larger trees.
Natural predators and parasites will help attack the sawflies. However, residents should check their smaller pine trees and ground cover, Bishop said.
It's easy to spot the sawflies since they are usually in groups, Scott said.
The larvae are an inch long, more than 1/8-inch in diameter and have varied color patterns, said Bruce Kile, Franklin County, Pa., service forester.
The European sawfly is green with cream and black stripes and eats the whole needle, Kile said.
The red-headed sawfly has a cream-colored body and leaves behind a straw-colored needle, he said.
To get rid of the sawflies, shake them off the branch into a bucket of soapy water or spray insecticidal soap on them, Scott said. Then cut off any dead needles.
If you're not sure whether the buds are damaged, slice one with a razor blade. A healthy bud will be green inside.