LEXINGTON, Ky. — In September 2012 the University of Kentucky (UK) College of Agriculture reported the USDA had confirmed the presence of spotted wing drosophila fruit flies in the south-central section of the state.

University entomologists had been monitoring for the insect since it showed up in neighboring states in 2010. In the report, UK extension entomologist Dr. Ric Bessin, a fruit specialist, warned growers the somewhat newly arrived species of drosophila fly would become a major problem for raspberries, blackberries, blueberries, grapes and strawberries for years to come.

Since then, Dr. John Strang, a fruit and vegetable crop specialist and extension professor at UK, has agreed the spotted wing drosophila will be a problem for the state’s peach and small fruit growers. At the same time, he mentioned another threat to Kentucky’s fruit producers: The brown marmorated stinkbug, which primarily attacks tree fruit such as apples, peaches and Asian pears.

Bessin explained both these pests both came to the United States from Asia. “There is the potential for these insects to hit our fruit crops pretty hard,” he added.

The reason for such devastation is these foreign insects do not have natural enemies in place here as they do in Asia. Entomologists are hoping over time new natural predators will be identified, thoroughly evaluated and then used in producers’ integrated pest management programs to keep the pests in check.

“With the brown marmorated stinkbug, I think we are still a few years away from serious problems,” Bessin said. “We may find them in certain areas, but it will take a long time for the numbers to develop.”

In the future, however, the problem is going to be serious because the stinkbug can attack tree fruits from just after petal fall until all the way through the harvest.

This long period of vulnerability means growers will need to monitor and treat as necessary over a three- to four-month period.

And, said Bessin, “Insecticides commonly used in our orchards are not effective against the brown marmorated stinkbug.”

With the spotted wing drosophila, growers are going to have to begin sampling this year. This tiny fruit fly has such a short life cycle that it can generate many new generations in a single season. If growers do find it they are going to have to change what they do during the harvest to avoid heavy losses.

Bessin said the drosophila is an insect that during most of the season, is probably not even in the plant. Only after the fruits begin to turn color and soften is when the insects begin to move into blueberry, raspberry, blackberry and strawberry plantings.

Growers will need to start trapping the last few weeks before crops ripen, and then if they find it they need to start a preventive spray program to keep the crop from getting infested.