Dry Summer Brings Blessed Relief From Biting Insects

Many folks have been spending more time outdoors during the pandemic, and fortunately there were fewer bugs around to bite them.

Dry conditions across parts of the Northeast led to a dramatic drop in bitty biters like mosquitoes and ticks this summer, officials said. That's leading to an anticipated reduction in bug-borne diseases.

In Maine, the preliminary number of cases of Lyme disease through Sept. 7 was 626, which was tracking well below the record 2,167 cases recorded in 2019. There were similar drops, so far, in two other tick-borne illnesses, anaplasmosis and babesiosis.

Ditto for mosquitoes. The state reports fewer of them were caught in traps this summer.

"We have more time to get out in the woods, and there are fewer things biting you," said Allison Kanoti, state entomologist. "For us, it surely is a nice break."

Lyme disease is caused by a bacterium carried by infected deer ticks. It's often accompanied by a rash referred to as the "bullseye" because of its shape. Symptoms include fever, chills, headache, fatigue, and muscle and joint aches, officials said.

Early in the summer, there was a surge of ticks that made it seem as though it would be another bad year, but that changed as the weather became hot and dry, said Griffin Dill, tick lab coordinator at the University of Maine cooperative extension. 

By late summer, workers who were actively looking for ticks weren't finding them, he said.

The trend has carried through other parts of New England. Vermont, too, saw a drop in ticks this spring, when it did its surveillance, and mosquitoes this summer. Same for New Hampshire.

"This year's numbers are down about 42% over last year's numbers," said Patti Casey, of the Vermont Agency of Agriculture about mosquitoes. Neither Maine nor Vermont have recorded any West Nile virus or Eastern equine encephalitis in mosquitoes so far this year.

"It's like the one good thing that 2020 is doing for us," Casey said.

Abigail Mathewson, New Hampshire's public health veterinarian, said she believes the numbers of deer ticks are down, as well as the mosquitoes that cause equine encephalitis. The reason, she said, is a lack of moisture.

It was an exceptionally dry, hot summer, with much of northern Maine and New Hampshire experiencing significant drought. The drought is either killing ticks or forcing them deeper into leaf litter, where it's more humid. 

The drop in equine encephalitis is a result of fewer puddles and ponds for mosquitoes to breed in. And even West Nile, which is caused by mosquitoes that require less water to breed, has been down.

But the dearth of bugs, especially ticks, could be short-lived. A rainy fall could cause another surge, but experts said numbers are unlikely to reach last year's.

"We still have time through this period until the ground is covered with snow that the ticks may be able to come out," Mathewson said. "If we get some drought relief, we may see more of these ticks coming out."

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Associated Press writers Lisa Rathke in Montpelier, Vermont, and Michael Casey in Boston contributed to this report.