worms in my cherries

Asked June 15, 2015, 3:28 PM EDT

I have two cherry trees, bing or similar, and the last couple years we have been plagued with worms. Cherries will have tiny pinholes, and a tiny white worm, usually near the pit. I think the holes might be the worms getting out, but not sure. What are these and how do I get rid of them?

Polk County Oregon

1 Response

Cherries can be damaged by 2 different kinds of small worms: the spotted wing drosophila (SWD) and the Western Cherry fruit fly. SWD are recently arrived invasive pests of soft-skinned fruits; they damage fruit prior to harvest and before it is fully ripe. The adult SWD are about the same size as nuisance fruit flies which fly around ripe and over-ripe fruits. The worms from SWD are much smaller than those from Western cherry fruit fly. If the worms are from SWD, the suggestion is to harvest daily, perhaps a little bit earlier than usual, and then to either eat or process them immediately; if needed, you can freeze the fruit as soon as harvested, and then make preserves or syrup at a later date.

Please read these publications to determine which one describes what is occurring at your place including the damage you see on your cherries:

- Recognize Fruit Damage from Spotted Wing Drosophila (SWD) http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/19525/em9021.pdf

- Protecting Garden Fruits from Spotted Wing Drosophila http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/20883/em9026.pdf

- Western cherry fruit fly http://jenny.tfrec.wsu.edu/opm/displaySpecies.php?pn=150

But first, begin a simple science project on the kitchen counter to verify which flies are damaging the cherries. This project to rear the worms to adulthood will take about 3 weeks. It could turn out that you have both flies. Please do the following:

1. Place about 12 damaged cherries in a small a clear jar. (It’s okay if they beginning to spoil.)

2. Fold about a quarter section of paper towel into a small wad, and then place it at one side of the fruit. (The toweling will absorb juice from the spoiling fruit.)

3. Cover the container with a “lid” of paper toweling, and secure it with a rubber band; set the jar where you will see it every day but not in direct sunlight.

4. Check the jar daily but don’t open the lid. (If fruit is infested, adult flies are often present within 3 weeks.)

5. When you see adult flies, compare them with the pictures in the above publications.

Please let me know if you have further questions.