Small Fruit Alert: Spotted Wing Drosophila (SWD) - 2025

This includes late-season strawberries, red and black raspberries, blueberries, blackberries, cherries and late-season peaches.  

Males and females are showing up at about the same time this year, so finding males with their characteristic wing spots also means that females are present to lay eggs in the fruit.  Signs that SWD is present include soft areas on strawberries, juice on the receptacles of raspberries once the berry is pulled off, light-colored or soft individual drupelets on blackberries, and pinprick-sized holes in blueberries.  Sunscalding on strawberries and blueberries due to the heat we’ve had this year could be mistaken for SWD presence.

If you wish to monitor for SWD, this can be done using SWD lures or apple cider vinegar with traps, or red sticky cards.      

Cultural controls should be used as much as possible.  Fruit should be harvested frequently and thoroughly.  Any cull fruit should be removed from the field and bagged.  Landscape fabric in raspberry plantings makes it easier to keep cull fruit cleaned up off the ground.  Fruit should be refrigerated as close to 32 degrees as possible immediately after picking.  Plantings should be kept weeded and pruned, which will make the environment less favorable to SWD and allow sprays to infiltrate the canopy better. 

Many different insecticide sprays have very good efficacy on SWD, but this is dependent on good coverage and a weekly spray schedule, more or less.  That means that rotating pesticide chemistries is important to avoid resistance development.  Effective pesticides are in certain chemical classes, specifically the pyrethroids (Mustang Max, Brigade, Danitol), spinosyns (Delegate, Radiant), diamides (Exirel, Verdepryn), and if growing only blueberries, certain organophosphates (Imidan, malathion if at a higher rate) and carbamates (Lannate). Those using organic practices can use Pyganic or Entrust, but be aware that some SWD resistance to these products has already been found elsewhere.  Lannate and Brigade are restricted-use products.

Spotted wing drosophila may not appear on the labels of all of the products listed above.  In PA, a pesticide can be used for a pest not on the label as long as the timing, rate, site of application, re-entry, and pre-harvest intervals, and any other specifications stated on the label are observed.  If you are from outside of PA, consult the label and your state’s registrations for allowable products in your state.

For information in more detail, please see the following:

• Spotted Wing Drosophila Part 1: Overview and Identification
• Spotted Wing Drosophila, Part 2: Natural History
• Spotted Wing Drosophila, Part 3: Monitoring
• Spotted Wing Drosophila Part 4: Management