wormy blueberries

Asked July 12, 2018, 7:55 PM EDT

I have 12 blueberry bushes and been growing for about 10 years. As we've started harvesting we've noticed some berries are damaged. As we've looked more closely we've seen small worms have infested the damaged berries. Will this become a persistent year-over year issue? If so, how should I address? Dan Dorn

Kent County Michigan blueberries blueberry insects swd spotted wing drosophila

1 Response

Those are probably spotted wing drosophila (SWD) or blueberry maggot the native blueberry pest. I call SWD the spotted weapon of destruction. This invasive pest appeared in Michigan in 2010 and has become a real problem for home fruit growers and commercial blueberry, cherry and raspberry growers.
MSU has a whole website dedicated to this pest.
SWD is a small fruit fly which can lay its eggs under the skin of thin skinned soft berries. The fly takes about 2 weeks to mature into an adult and start the cycle again, so number build up in June as the first wild berries ripen and continue to build until the winter cold knocks the population down. SWD over winter as adults and a few survive the winter and start the cycle again as the first fruit ripen in the spring.
You will find a fact sheet for home owners located down in the middle of this page.
I recommend you harvest the fruit as quickly as possible to reduce the amount of time the fruit is exposed to the fly. There are a few insecticides available to home owners but most do not want to spray the fruit every 4 or 5 days.
Let me know if you have any other questions