Invasive species a growing problem for region

FILE - In this July 19, 2007, file photo, a Lymantria dispar moth caterpillar crawls along partially eaten leaves of a tree in Trenton, N.J. In July 2021, the Entomological Society of America announced it is dropping the common name of this destructive insect that is also an ethnic slur against a group of people: the gypsy moth. (AP Photo/Mel Evans, File)

Between now and May, if residents of the county don’t develop some type of a suppression plan, the outbreak of Limantria dispar — formerly known as the Gypsy Moth — could become “quite a large problem,” Sarah Johnson, a forest health specialist with the state Bureau of Forestry, told the Lycoming County commissioners at their meeting recently.

The outbreaks of the moths are happening around the entire state. In Lycoming County, the western and southwestern area closer to Clinton County are most affected.

Johnson said she has personally encountered trees with 600 egg masses on them.

“Those trees will be bare before summer,” she said.

The life cycles of the moth, which was first brought to this country in the late 1800s as an alternate silk source, include egg, larva, pupa and adult. The egg cycle, larva, pupa and adult stages occur over many months. The egg cycle occurs October through March, the larva cycle happens April through June, and July through September, the moth goes through pupa and adult cycles. According to Johnson, the stage for intervention occurs when they are in the small caterpillar (larva) stage in the May timeframe.

“So, we’re looking at between now and May if anybody wants to plan an intervention,” Johnson said.

In order to combat the problem in Pennsylvania, chemicals and biological pesticides are sprayed to suppress the moth population in high priority areas. Other areas can be classified as slow distress because the spread needs to be contained. In those areas chemical pheromones are sprayed because the population of moths are less.

“Pennsylvania is only in the suppression because we have been fully infested for a very long time,” Johnson said.

The problem of an ongoing infestation sustained for three years is the damage to the trees is significant. Typically feeding on the foliage of oak trees, the moths also will attack beech and black cherry as well as other species.

The state Department of Conservation and Natural Resources, which has oversight of the Bureau of Forestry, began its suppression program in the 1970s using fixed wing planes and helicopters to spray the substances. They also return and assess the amount of damage to the forests by the moths. She noted that for the last two years, DCNR has not been able to use planes to map the defoliation.

“This was all done from the ground again, unfortunately, but it’s a large scale problem that we probably missed quite a lot,” Johnson stated.

Compounding the problem is the fact that the state does not spray private lands. That is up to the landowner.

“Right now, even if we were wanting to spray private land, if we had the money to spray private land, we couldn’t logistically do that. There’s just too much to spray generally. The scale of the problem is just huge right now,” Johnson said.

If property owners with a high percentage of trees that could be affected would join together to purchase the service of aerial applicators, the costs would be decreased.

“If we’re not going to do it, what makes the most sense is to gain the economy of scale for the private landowner by putting something together at a larger population diversity,” Johnson said.

“I have my own thoughts about how and what would be a good way for us to integrate the private program into the state’s free program again. But the long and short of it is, right now, we are maxed out on what we can do with only half of the public proposed acres to spray in the spray program,” she said.

Johnson did offer a ray of hope in the form of wet weather in April and May.

Back in the early 90s, a fungus was introduced, which, along a virus has built up in the environment. The fungus as well as a virus have the potential to cause the infestation to crash, Johnson said.

“So, if we have a wet spring, the fungus can be really active. The virus travels more easily with rain splash. We see a wet spring, we could see a shortening of this, but we don’t know that until we get there,” she added.

For more information on this invasive species visit the DCNR website: https://www.dcnr.pa.gov/Conservation/ForestsAndTrees/InsectsAndDiseases/GypsyMoth.


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