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09/21/2017 12:00 AMWe've all been there. An unwelcome guest comes over without invitation and suddenly they're impossible to get rid of. And no, we're not talking about a dinner party. Ask any homeowner and they'll likely have a story of a time when gypsy moths took over their trees and how hard it was to not only get them to leave but to keep them away for good.
The problem has been a nuisance for local homeowners. For the third summer in a row, gypsy moths - or Lymantria dispar dispar - plagued eastern Connecticut.
Rich Sala of Bartlett Tree Experts in Essex says that 2017 was an even worse year for gypsy moths in Connecticut than 2016. Right now, he says that it is hard to tell but it looks like the situation will most likely be somewhat similar next summer.
"Shouldn't be quite as bad because many [caterpillars] were killed by the fungus," says Sala. The fungus is called Entomophaga maimaiga, and it is known for keeping the gypsy moth population under control.
The fungus did some damage to the population of gypsy moth caterpillars - a factor that did not contribute as much last year thanks to conditions of the local climate.
"We dodged the drought bullet this year, which is why the fungus kicked in with reports of dying or dead caterpillars from 86 towns," says Kirby Stafford III, chief scientist and state entomologist of the Connecticut Agricultural Experiment Station (CAES).
Stafford has published a presentation on "Gypsy Moth Outbreaks in Connecticut, Past, Present, and Future."
In the presentation, he recounts the history of gypsy moths in the state, the outbreaks that have occurred since the species was first identified in Stonington in 1905 - CAES surveys for gypsy moths each year as a part of the Connecticut's Forest Health Assessment which is carried out starting in late June and ending in early August.
The reason, he reports in the presentation, that the gypsy moth infestation has been so bad over the past few years (2015-2017) was droughts.
So, without the drought this year, Stafford reports that more than 90 percent of the gypsy moth caterpillar population was killed off by fungus which will result in reduced gypsy moth activity in 2018, as well. Because of the fungus' growth this year, it is likely that next year more fungus will grow back - this will protect trees from future outbreaks. It all depends on the rain, which allows the fungus to grow.
"The fungus produced in a year makes two times the spores. There will be a lot of resting spores out there which we will rely on next time we get to the next big gypsy moth outbreaks which come every 10 years or so," says Stafford.
However, there will still be some areas in which gypsy moth activity will remain high next year.
"We did see many pockets where the adult moths were flying and laying eggs who will hatch in 2018," says Sala.
Sala says that right now, there is not much that people can do to prevent the gypsy moths from coming back next year.
"They are in the egg mass stage right now and not much we can do effectively to prevent next year caterpillars from hatching," says Sala.
However, there is a treatment that can be carried out after the caterpillars hatch in May and again in June.
"Foliar treatment is a spray application to target the gypsy moth in the caterpillar stage as they are feeding," says Sala. "This is the most effective treatment."
Stafford says that in the areas where gypsy moth egg masses are visible, people can try spraying a half-and-half mix of oil and water on the egg masses.
In terms of damage, Stafford says that most trees have re-leaved to varying extents. He says that if the trees are re-growing their leaves, then there is a good chance they will make a full recovery. Not all trees are experiencing regrowth, though.
"Most trees will survive a single complete defoliation unless there are other stressors at work," says Stafford. "There are some that have not and some trees were lost over the course of the three-year outbreak."
Currently, Sala says that he and his colleagues at Bartlett Tree Experts are dealing with a lot of trees that died last year as a result of total defoliation.
The good news is that the worst of the outbreak is over.
"We're not going to see the kind of outbreak like we saw this year or last year, you know the huge outbreak is essentially over," Stafford says, but adds, "We won't know exactly where and what to expect next year until we do our egg mass survey this winter."