Spotted Winged Drosophila (SWD) is a new invasive pest found elsewhere in the U.S. that we expected to arrive in Iowa eventually. Unfortunately, that wait is over as we have found several instances of this pest across IA. SWD are in the same family as common fruit flies, however, unlike the common fruit fly they do not lay eggs in rotting fruit. Instead, females lay eggs in fresh, ready-to-harvest fruit using a unique serrated ovipositor. They will lay eggs in any soft skinned fruit such as aronia, blackberry, blueberry, grape, raspberry, and strawberry and possibly even tomato and apple just prior to harvest. Infested fruit are unmarketable and decay very quickly as larvae consume it. Thus far this year, they seem to be showing up in raspberries and blackberries.
Monitoring for this pest can be done using a simple trap. For instructions on building a trap, visit the Michigan State SWD homepage. It is essential that traps are placed within the fruiting canopy and filled with REAL apple cider vinegar (purchased from your favorite grocery store). Apple flavored vinegar does not work. Male SWD are easiest to identify with a single black spot at the tip of each wing. Males also have two black bands on their front legs. Females do not have the black spots on their wings or black bands on their legs but can be identified by the serrated ovipositor on their posterior end.
Preventions for SWD are the standard sanitation procedures; remove all rotting fruit and harvest frequently to reduce habitat potential. Danitol, Delegate, Entrust, and Malathion are common products used to control SWD but be sure to check the Midwest Small Fruit and Grape Spray Guide or the Midwest Tree Fruit Spray Guide for products and rates on specific crops. Also be sure to follow appropriate harvest intervals as found on page 60 in the Midwest Small Fruit and Grape Spray Guide and page 46 in the Midwest Tree Fruit Spray Guide.
Dr. Rick Weinzierl, Entomologist from the University of Illinois, suggested that we may need to reduce spray intervals from every seven days to every five days for products such as Delegate, Brigade, or Mustang Max to achieve adequate control of SWD in brambles. For those of you who are certified organic, Entrust is your best option.
Below: Control options for SWD courtesy of Celeste Welty, Extension Entomologist, Ohio State University. Dated 2013. Always read and follow the label before applying any pesticides.
! Restricted Use Pesticide
§ Not allowed in greenhouses or high tunnels
X means that the product is NOT ALLOWED for use on that crop
- Michigan State SWD Website
- Oregon State SWD Website
- UC Davis SWD Website
- Penn State Extension SWD Website
- North Central IPM Regional Pest Alert
- Monitoring for SWD, Lincoln University
- Integrated Pest Management of Spotted Winged Drosophila, Lincoln University
- The most current pest control information can be found in the Midwest Small Fruit and Grape Spray guide or the Midwest Tree Fruit Spray guide.
- Trece SWD Lures