Gypsy moths are moving in to feed on our oak trees.
The Allegheny National Forest and the Pennsylvania Department of Conservation and Natural Resources (DCNR) are ready.
"Gypsy moths are one of the most studied insect systems," according to U.S. Forest Service Entomologist Rick Turcotte.
"What makes gypsy moths a big issue for us here in the United States is they have a large host range - the trees or shrubs that they feed on," he said. "It's over 300 species, and oaks are one of their favorite hosts."
European gypsy moths have been in the area since about 1984 and were first introduced in Massachusetts in the 1860s, according to Turcotte.
When the caterpillars are tiny, they move with the wind. A caterpillar launches a silk thread. When the wind hits the thread, it carries them away "as far as the wind can take them," Turcotte said.
A good landing zone is one they can eat.
"If they land on something, they try it," he said. "If it's food for them, they stay there, if not, they do this ballooning again."
The moths can also hitchhike on firewood and camping gear.
Officials ask that people coming to the area for or after a camping trip inspect their gear for egg masses.
Hitchhiking and ballooning are important strategies for gypsy moths to spread out.
The egg-laying adult females do not fly.
"The female is flightless," Turcotte said. "She's basically an egg-laying machine."
Depending on the quality of the host plant, one female can lay 75 to 1,000 eggs.
The eggs hatch in April and May, but the evidence of the mass stays.
Officials count egg masses to determine where the gypsy moth infestations will be worst.
Andrea Hille, a silviculturist - a scientist concerned with the growing and tending of trees - with the ANF, said the agency looked for egg masses over the winter, focusing on stands of oak and developed recreation areas.
"This year on the ANF we surveyed 20 sites across the forest," Turcotte said. "We found gypsy moth egg masses at 17 of the 20."
There were enough masses at six of those locations to meet the agency's treatment threshold.
The threshold levels are different based on the area, Hille said. Fewer masses would be seen as cause to treat in developed recreation areas than in other areas.
Having a forester count egg masses is only one way agencies monitor gypsy moth activity.
When the caterpillars start eating leaves in the spring, the extent of the damage can be seen from the air, and even by satellites. "And we get lots of reports from the public," Turcotte said.
"We started seeing an increase last year," DCNR Bureau of Forestry District Manager Cecile Stelter said. "We started getting a few phone calls and noticing a larger population."
"It's increasing," Turcotte said of gypsy moth activity. "Gypsy moth is what we call an outbreak pest. Historically, gypsy moth cycles every ten years. It's been a little more than that since we had a breakout."
There are other insects on the forest that are causing concerns.
Cicadas are expected in large numbers, but they are familiar, native pests and do not kill trees. Fall webworms defoliate trees, but not until the fall.
Officials are watching for emerald ash borers and hemlock wooly adelgid - exotics that kill trees.
Healthy oaks can bounce back from significant defoliation, Turcotte said, but when 50 to 60 percent of their leaves are eaten in a season, they refoliate - diverting energy and nutrients from other needs. With fewer leaves, the tree has less ability to create energy, so the problems are magnified.
"We did not experience any defoliation on the ANF due to gypsy moths last year," Hille said. "This year we will be watching very closely to see what happens with defoliation."
"For the ANF to consider any sort of a suppression program, we would monitor to see what occurs," she said. "It's a large forest. We need to think about where are the important resource areas and what is actually occurring in terms of defoliation."
Treating for gypsy moths must take place in the early spring, "very early in the life cycle of the caterpillars," Hille said.
DCNR completed a three-week spraying program on May 31, but Warren County was not one of the areas treated. "There were 82 treatment blocks for a total 42,014 acres," Stelter said. "We hadn't had a spray program for a number of years."
Helicopters spray an insecticide onto leaves. The material sticks to leaves and, when the gypsy moth larvae eat those leaves, they die.
The agencies count on a little help from the moths' natural enemies.
"In addition to the spraying, there was also a virus and a fungus that occurs in the soil," Stelter said. "We hope that the spraying will help and that the virus and the fungus will kick in. There are also some birds in particular the black-billed cuckoo."
Most birds won't eat the caterpillars because they have long spines that irritate the birds' eyes. The cuckoos' beaks are long enough that the spines are not a problem for them.
"We hope for a good population of cuckoo birds," Stelter said. "They're a native population."