Spotted wing drosophila on a strawberry

Spotted wing drosophila on a strawberry
Image Credit: Washington State University Extension

BEAUFORT — The fruit-eating spotted wing drosophila has been found in a strawberry patch in Beaufort County for the first time, and growers should take action to protect their harvests.

Clemson University Cooperative Extension agent Zachary Snipes said the fruit fly was found in a patch Friday and had already damaged 70 to 80 percent of the grower’s red fruit. The fruit fly has been found in parts of South Carolina before, but is more common from summer to fall.

An unusually warm winter likely allowed the pest to infest Lowcountry strawberries so early in the year, Snipes said. The Lowcountry strawberry season typically ends before spotted wing drosophila becomes a problem in other parts of the state in June or July, he said. This year, however, growers have been picking strawberries since December, three months ahead of schedule, Snipes said.

Adult spotted wing drosophila attack ripening fruit, unlike common fruit flies that typically seek rotting fruit, Snipes said. The adults lay their eggs within the fruit, causing the fruit to become soft and slightly darker in color. The fruit must be dissected to examine whether larvae are inside. The larvae appear white, clear or cream in color. The young flies will eat a hole into the fruit and leave as adults, looking to lay eggs in other fruit.

Spotted wing drosophila larvae is dug from a Lowcountry strawberry.

A spotted wing drosophila larva is dug from a Lowcountry strawberry.
Image Credit: Zachary Snipes / Clemson Extension

“If you have them, you have to dispose of all the red fruit,” Snipes said.

Growers should begin scouting fields, he said. The fly also can cause significant economic damage to cherries, blueberries, raspberries and blackberries.

Growers will need to spray insecticide weekly, at minimum, and after rainfall to mitigate damage caused by spotted wing drosophila. Effective insecticides to this serious pest are toxic to bees, so treatments should be applied at night when bees are not actively foraging. Detailed spray recommendations for spotted wing drosophila can be found online in the 2016 Southeast Regional Strawberry Integrated Pest Management Guide.