Spotted wing drosophila (SWD) fruit flies have been captured in traps placed in fruit as part of the Wayne County Extension Integrated Pest Management (IPM) program in several locations within the county over the past couple of weeks. The presence of SWD indicates that fruit growers, especially those who produce any kind of raspberries, blackberries, blueberries or grapes need to take preventative action.
Unlike the common fruit or vinegar flies that are a pest of over-ripe fruit, the SWD is able to damage fruit as it starts to ripen. Each female fly can lay between 300 to 350 eggs. Under optimum conditions only 8 to 10 days are needed to go from egg to adult and there are multiple generations per year. Without preventative treatment, numbers can quickly build to high levels, making that fruit generally un-marketable. At this point, the only reliable control method available is the use of chemical insecticides.
Insecticides generally have to be applied every 5 to 7 days. Home gardeners and commercial fruit producers alike are encouraged to rotate between chemical classes to reduce the possibility of chemical resistance developing in the SWD population. More information about the SWD and its lifecycle, along with a chart of insecticides that can be used to control the pest and timing of insecticide applications can be found at: http://u.osu.edu/pestmanagement/info/swd/ or contact the Wayne County Extension office at 330-264-8722.
A salt-water test provides a quick diagnostic to determine if SWD have infested fruit. Details on how to perform the salt-water test are available at the previously mentioned web site.
Other information can be found in the resouces below.