A spotted wing drosophila rests on a raspberry. (Courtesy Timothy Baker)
Shoppers hoping to buy berries, peaches and grapes at farmers markets in Missouri may be looking a little bit harder this summer due to a newly arrived pest that is damaging crops across the state.
The pest, called the spotted wing drosophila, resembles an ordinary fruit fly. But it is much deadlier. It kills healthy fruit by making a tiny slit in a fruit’s skin and laying eggs inside. In two weeks, a female fly can lay more than 300 eggs inside cherries, peaches, raspberries, blackberries, strawberries, blueberries and grapes. A couple of adult flies can become thousands of flies in a few months, according to Jaime Piñero, an integrated pest management specialist at Lincoln University.
“We know the pest is everywhere in Missouri. It is a state-wide pest problem,” Piñero said. “We have monitoring traps farmers can get for free. The best way to control this pest in the short term is insecticides.”
But since the larvae feed under a fruit’s skin, farmers are having a hard time learning their crops are infested before it’s too late.
Ronda Thiessen identified drosophila on her cherries on Sandy Creek Farm, which she owns with her husband Randy in Franklin, Mo. But the Thiessens still lost about 35 percent of the year’s crop.
“We had to stop harvesting because we couldn't get enough good fruit to take to market. Part of our season was just gone,” Thiessen said. “And they have moved into, progressively, into our other fruit as it’s getting ripe. They have started reproducing in the peaches.”
Thiessen worries the Jonathan apples they will harvest in a few weeks could be next.
In the Kansas City area, Mule Barn Berries also had an infestation of the fly in their blackberry crop.
“We didn’t lose a terrible amount – 500 pounds out of our crop of 15,000 pounds -- but it was very stressful,” said Renee Seba, who runs the farm with her husband Charlie. “We went to spraying every week and we haven’t had any problems since.”
The spotted wing drosophila is native to Japan but was first discovered in the U.S. in California in 2008. The fly has since been detected across the country, including in Illinois, Iowa and Colorado last year, and now in Nebraska as well as Missouri.