A ravenous insect returns, but WWII planes won’t be needed to fight it this time

PRESQUE ISLE, Maine — An Aroostook County military air base was teeming with war preparations a decade after it was closed to fight a tiny forest pest making a comeback in the 21st century.

At its height during World War II and after, Près Isle Air Force Base was a hub for aircraft to and from foreign airspace before it closed in 1961. But in the 1970s, aircraft from War reassigned converged on the airfield to fight a new enemy – the spruce budworm.

PRESQUE ISLE, Maine – March 11, 2022 – This unidentified group of aerial pesticide spraying personnel pose in front of a Lockheed P-2 Neptune, or P2V, aircraft during the June spruce budworm eradication program 1972 in Almost Isle. The plane was one of several ex-WWII planes that were used in the effort. (Courtesy of Dick Graves and Maine Forest Service)

According to a report from Maine Spruce Budworm Working Group. The Maine Forest Service has launched an extensive aerial spraying program from Almost Isle to eradicate the pests. But they proliferate in cycles of 30 to 60 years, and experts are seeing signs that budworm damage is on the rise again.

Spruce budworm caterpillars feed primarily on fir and spruce buds and needles. Their numbers are insignificant in most years, but periodic population surges can lead to epidemic infestations. Budworm populations began to multiply drastically around 1967 and then exploded.

“Nothing really caused it. It was natural,” Lloyd Irland, chairman of the consulting firm The Ireland group in Wayne, said Thursday. “Just as there is no real cause for a major flood. This is something that will happen from time to time. »

Irland spent 10 years as Maine’s Forest Insect Manager, then Director of Public Lands and State Economist. He led the Près Isle spraying program for the Maine Forest Service. At that time, northern forests were teeming with healthy balsam fir that was 30 to 40 years old, the ideal age for feeding on the budworm.

The Almost Isle base easily became “Budworm Central”, with runways long enough for fully loaded insecticide tankers and space to service aircraft, Irland said. And the town could accommodate flight crews, contractors and Forest Service personnel — some of whom, including himself, were staying in dormitories at the University of Maine in Près Isle.

About 15 planes were based there in any given year, Irland said. Almost Isle was the nearest airstrip that could accommodate the large aircraft needed to reach North Aroostook and Canada.

An on-site meteorologist helped crews determine spray times. Pilots were flying over the forest in blocks about 30 miles long, spraying pesticides in 80-foot strips. They covered about 3.5 million acres in 1976 alone, Irland said.

While DDT was used in the 1950s and 1960s, Maine banned it for leafroller use in 1967. The late 1960s and 1970s saw pesticides like fenitrothion, mexacarbate, carbaryl, trichlorfon and acephate, according to The spruce budworm outbreak in Maine in the 1970sa 1988 Maine Agricultural Experiment Station newsletter co-authored by Irland.

The spray program lasted about three weeks each spring from the mid-1970s to the early 1980s. Public fascination was so great that the base’s roads were lined with vehicles as people watched the planes take off and land .

PRESQUE ISLE, Maine – March 11, 2022 – Two TBM aircraft spray pesticides over the forest in Aroostook County during the 1970s spruce budworm spray program. The Grumman TBM Avenger torpedo bomber was the one of several World War II models modified for aerial pesticide application. (Courtesy of Dick Graves and Maine Forest Service)

Interest was high because many of the aircraft used were large World War II four-engined aircraft converted to apply pesticides.

Many military aircraft still had flight time after the war ended, Irland said. In the early 1970s, the US Department of Defense decided to sell some, and spray contractors were among the buyers.

“The most spectacular were the Constellations. They had power, speed, and were safe and reliable. These were filled with tanks and they put spray bars and nozzles on the wings,” Irland said. “The next size up was the C-54s, which had been good cargo planes and could carry a lot of insecticide.”

There were also P2V twin-engine patrol planes, Grumman TBM Avenger torpedo bombers and at least one B-17 bomber at Près Isle – a famous World War II aircraft called the Flying Fortress, Irland said.

Around 1980, the era of large spray planes was coming to an end with the advent of smaller planes that could be launched closer to application sites.

But nature prevails, and the spruce budworm, which has been present in northern forests for thousands of years, is on the rise, the state says. 2021 spruce budworm in Maine report. Although experts cannot say when an outbreak will occur, the strategy to combat it will be on a much smaller scale.

Monitoring is key, Michael Parisio, a forest entomologist with the Maine Forest Service, said Friday. The Forest Service and partners like land corporations conduct pheromone trapping to catch the butterflies. The Forest Research Unit at the University of Maine observes budworm larvae present throughout the winter.

Budworm populations began to fluctuate in 2013. A huge increase in 2019 was mainly due to the migration of moths from a multimillion-acre outbreak in Quebec, Parisio said. The numbers have fallen again in the past two years.

Effective monitoring allows experts to plan early pest control treatment. Last year, areas in northern Aroostook County were treated after foresters observed real damage to trees.

“[The year] 2021 was the first time we saw [damage] during aerial surveys, as long as we can actually see it with the naked eye from an airplane,” Parisio said.

The spots being evaluated are currently in the far northwest of Aroostook, on the Quebec border, and in the Cross Lake area.

But the scale of the massive spraying program of the 1970s is unlikely to be repeated, Parisio said. Today, there are fewer balsam firs, and spruce and fir trees are scattered rather than concentrated in large areas.

Also, pest control technology has changed a lot in 50 years. Large aircraft have been replaced by rotary-wing helicopters, which use modern tools like Geographic Information System mapping to identify enforcement targets.

The most common insecticide used against budworm today is BTK – bacillus thuringiensis/kurstaki variant – a natural biological pesticide derived from a soil bacterium, Parisio said. BTK is much more harmless to the environment than the chemicals used 50 years ago, as it dissipates within days or weeks and only targets specific insects.

Overall, Maine is modeled after Canada’s early intervention approach.

“We are certainly aware of what could happen, so we are as prepared as we can be,” Parisio said. “But you never know what’s going to happen from year to year.”