Dear Marylou,

Thank you for your question. 

You can find some recommendations for cultural controls of spotted wing drosophila in this University of Minnesota Extension resource: https://extension.umn.edu/yard-and-garden-insects/spotted-wing-drosophila#cultural-controls-992611

In particular, two avenues are:

Sanitation

- Frequently harvest crops to ensure ripe fruits are not in gardens for extended periods of time.
- Remove and destroy any old fruit that remains on stems or that has fallen to the ground.
- Once infested or fallen fruit has been collected, place it in a plastic bag and seal it tightly.
- Fruit in clear bags can be left outdoors where the heat from the sun will kill any flies in the bag.
- Plastic bags can also be placed in the trash.
- Do not compost this material as that method is unreliable in killing SWD.
- Do not bury infested material as research has found that SWD can survive being buried as deep as 18 inches.

Exclusion

- Netting can be used over a more permanent structure, such as a small high tunnel, or placed directly over the row like a floating row cover.
- The cover prevents SWD access to developing berries and can potentially reduce the infestation.
- One drawback is that the covering would have to be opened at each harvest, which could provide SWD access to the fruit.
- Use a fine mesh netting: 80-gram insect netting has been shown to provide good results.
Coarser netting will allow SWD to pass through and infest fruit.
- Netting can also provide protection from birds and hail.

You might also consider the possibility of blueberry fruit fly: https://extension.unh.edu/resource/blueberry-fruit-fly-fact-sheet

Similar cultural controls, including frequent harvest, can be used to mitigate damage from the blueberry fruit fly as well.

Best,