CHERRYFIELD — Maine is reaping the benefits of the wild blueberry crop this season, but a new insect pest that arrived last year should keep growers wary.

David Yarborough, a University of Maine professor of horticulture and the state’s leading expert on blueberries, said Wednesday that fruit size and yields are “average or above.” He noted that earlier rains supplied moisture but interrupted harvesting. And while growers have been lacking rain since Aug. 16, anticipated thunderstorms in the near future are expected to replenish that moisture.

Edward Flanagan, president and CEO of Wyman’s of Maine, the country’s largest marketer of wild blueberries, was enthusiastic about this year’s harvest so far.

Before a tour of his company’s processing plant in Cherryfield on Thursday, Flanagan pointed out that Washington County, Maine’s leading producer of wild blueberries, was yielding “a really good crop.”

Flanagan opened the plant to reporters to showcase the company’s recent $1.4 million investment in new, energy-efficient refrigeration equipment with the aid of a state program. The plant processes blueberries and other fruit including strawberries, blackberries, raspberries, cranberries and imported mangos.

But even with all the positives of this year’s crop, Yarborough noted Tuesday in his latest Cooperative Extension blog for growers, there is an increased presence of spotted wing drosophilia — a type of fruit fly that damages blueberries. The pest, which first arrived in Maine last year, has been captured in traps in all blueberry growing regions. The most were trapped in the southern coastal areas.

Yarborough urged growers to monitor fields for the insect, and if traps catch a single male or multiple females, fields should be harvested immediately or protected with an insecticide.

“I still believe we are safe from fields having significant damage as we have not been finding [fruit fly] larvae in fruit samples as of yet,” Yarborough wrote in this week’s blog.

“Also, it looks as if the early harvesting that has been taking place all over the state will certainly pay dividends this year if we can get much of the crop in before significant damage starts to be detected,” Yarborough continued. “Just remember that based upon last year’s monitoring, this pest can explode in numbers very quickly from just a few flies to hundreds [per] trap … so do not relax too much!”

“We’re still very worried about that,” said Flanagan, referring to the fruit fly. The company, which has 9,000 acres of blueberry land in the U.S., is treating fruit to protect it from the pest.

Wyman’s, which also has facilities in Deblois, Wesley and Jonesboro, processes 400,000 pounds of wild blueberries daily at its Cherryfield plant — the only one that conducts year-round operations. Its total Maine employment for the company is about 140 workers.

The company’s customers range from national grocery chains, food service businesses and grocery manufacturers such as General Mills and Sarah Lee.

In order to keep pace with rising production, the company needed to nearly double its refrigeration capacity. It opted for a more costly system that would generate significant energy savings, and an investment was made possible by a $260,000 incentive provided by Efficiency Maine, a program of the Maine Public Utilities Commission.

Wyman’s expects to save more than 1 million kilowatt hours of power and $90,000 a year in energy costs, according to Bob Stanley, director of engineering at the plant.

Back in 2006, Wyman’s made investments to upgrade one of its large refrigeration systems. That modernization increased capacity and efficiency, and it was expected to lower electricity costs by $40,471 annually. The company also invested in more efficient lighting at its 80,000-square-foot Cherryfield plant that year, improvements expected to generate an additional $17,800 in annual savings in electricity costs. The 2006 investments were made possible in part by cash incentives provided by Efficiency Maine, which helps Maine businesses reduce energy costs while improving the work environment.

Refrigeration is the “lifeblood of blueberry businesses,” said Paul Badeau, a spokesman for Efficiency Maine.

The new improvements at Wyman’s, which are functioning for this year’s harvest, include a new state-of-the-art air curtain that replaced conventional roll-up doors. The doorless system is safer and more effective at maintaining freezing temperatures, company officials noted.

“Wow. That’s a big difference,” said a reporter who walked through the air curtain opening into the area where frozen blueberry products are stored.

The temperature inside is kept between 0-5 degrees, said Stanley.

Flanagan also mentioned that Wyman’s is building a new processing plant on Prince Edward Island in Canada. The company needs additional processing capacity in that country, he said, but “it will have a bearing on our business in Maine — a positive bearing.”

He also explained that with Wyman’s trucking Canadian blueberries to its plants in Maine, when shipments arrive at the plants, harvesting operations in Maine have to be temporarily halted until the sudden influx in inventory can be processed. During the brief harvest season, ripe blueberries fall to the ground and are lost if they are not raked in time.

Flanagan suggested that Canada is more friendly to business than the U.S., but he lauded the Maine program that helped his company with a significant capital investment project.

“There are investment tax credits and grants and things like that behind a big capital investment project that are very, very hard to find here in the states anymore,” he told the tour group. “Efficiency Maine is an outstanding example where a need on our part to build something is rewarded and actually done the complete, right way. We needed more cold … and with Efficiency Maine and its incentive, it made a lot of sense for us to do it absolutely the right way.”