rain on window
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A record rainfall for Portland on Monday helped temper April's stretch of dry, fire-prone weather, greening up places like Deering Oaks, but there's a many-legged downside.

Invasive insects may crop up where they haven't been seen before.

On Monday, Portland set a daily record for rainfall with 3.13 inches of rain, breaking the old record of 1.53 inches set in 1921, according to Margaret Curtis, meteorologist with the National Weather Service. Rainfall records go back to 1941.

A weekend storm helped the state rebound from several weeks when fire danger peaked at high on state advisories. For weather watchers, the nor'easter, which dumped 4 to 5 inches of rain from Portland up the mid-coast through Waldo County, evened out a month known for its showers but that had been inordinately dry.

"Three weeks of dry and two really wet days, it all comes out really close to normal," Curtis said.

For Allison Kanoti, forest entomologist with the Maine Forest Service, the dry-to-wet cycle meant a case of good news, bad news in the world of bug hunting. Deering Oaks is the place where state scientists converged two years ago to put out an alert about invasive pests, particularly the Asian longhorned beetle. Today, Maine is still free of the beetle, but state scientists said the recent storm set the stage for the public to check forests for signs of unwanted pests.

"If folks have storm damaged trees, it's a good time to look for signs of Asian longhorned beetle," Kanoti said yesterday in an interview.

The beetle causes structural damage to trees, so maples weakened by the beetle may end up succumbing in a storm like last weekend's nor'easter, she said.

Good news on the weather front is that the recent rainfall - which the weather service noted has brought Portland up to near average for monthly precipitation - also helped fortify trees against invasive insects.

"Getting a little bit more rain will help support the trees, because drought is expected to cause decline to be more rapid," Kanoti said.

The bad news on the weather front is that the recent storm may have spread another invasive pest - the hemlock woolly adelgid, which can go airborne and find new woods to damage.

"The storm like the one we had this past week can move the adelphids out further," Kanoti said. "This is the time of year that adelphids can be moved on winds."

Hemlock woolly adelgid, a small, aphid-like insect that originated in Japan but arrived in the United States in the 1950s, causes premature needle drop and twig dieback, and eventually, death of host trees. This past winter created ideal conditions for the invasive forest insect, and it was found recently in Alfred, Arundel, Biddeford and Kennebunk, according to the Maine Forest Service.

The adelgids survived quite well over the winter, and people are likely to see them in new places, Kanoti said.

Meanwhile, scientists hope they don't see the Asian longhorned beetle in Maine. The pest attacks so many types of hardwood trees, officials fear billions of dollars worth of damage to the economy and severe effects on the environment if it becomes established here.
Since 2009, when state scientists organized volunteers for a search for the Asian longhorned beetle around Deering Oaks, Kanoti said some tough lessons have been learned in Boston and Worcester, Mass., where infestations were detected. The Worcester, Mass., infestation was found two decades after its infestation. Due to the delay in detection, Worcester had to remove 30,000 trees, she said.