Life may be a bowl full of cherries infested with bugs Jan. 14, 2016

Spotted wing drosophila
Spotted wing drosophila Photo courtesy University of California

It’s bare-root season, when local nurseries have dormant trees and plants for sale.

These are usually less expensive than plants sold in large tubs filled with soil. Roses are among the popular bare-root sellers.

The cool season is a good time to plant trees and shrubs because the roots will benefit from winter rains and have a chance to expand into the soil.

When digging a hole for a new plant, try to dig several days after it rains.

If you dig when the soil is muddy, you’re likely to compact the soil.

Last week I chatted up Bob Scoville, a patient and knowledgable volunteer with the Glenn County Master Gardener Program.

He said he recently learned some pretty interesting things about cherry tree pests, and was eager to share the news with others.

That’s how these Master Gardeners are. They learn something new, they want to tell us all about it.

The critter is the spotted wing drosophila, and its prime targets are cherries and berries.

You can read all about it here:

The critter is among what Scoville refers to as “vinegar flies,” or flies that find their way to rotting fruit.

What is especially alarming about drosophila is that it lays eggs in healthy fruit as well as fruit that has already dropped to the ground. The buggers’ favorite treats are soft-skinned fruit including cherries, raspberries, blackberries, blueberries and strawberries. They’re also known to go after boysenberries and nectarines.

How it works is the adult fly lays her eggs just under the skin of your otherwise perfectly good cherry. The eggs become maggots, and the maggots nibble their way to adulthood.

The University of California Integrated Pest Management website notes that after the otherwise perfectly healthy fruit starts to get nasty, other common vinegar flies will come along and lay their eggs in that same fruit.

The maggot eventually gets full, grows to full-grown, exits the fruit and immediately begins to find a way to procreate. The mating begins about mid May, or when temperatures reach 68 degrees. Things slow down when its hotter than 86 degrees.

Ten generations of the flies may occur each year.

The pests were originally from Japan and are relatively new to California.

Before planting a cherry tree, Bob suggested a homeowner wait until spring and test to see whether the drosophila are in your neighborhood.


In early May, grab a one-quart plastic yogurt container and drill 10-16 holes, about 3/16 of an inch in diameter around the upper side of the container.

It was funny that Bob was so specific about the dimensions of the holes, but there must be a reason, so I just ran with it.

Then add about 1-2 inches of pure apple cider vinegar to the container. (Flavored cider doesn’t work, Bob said knowingly).

Then, here’s the real trick, add a drop of unscented dish soap.

The soap stays on the surface of the liquid, providing a layer that coats the surface tension.

The bugs are attracted to the cider, find themselves in the liquid, fall under the surface of the liquid and can’t break the surface.

The drosophila can be distinguished from regular vinegar flies because the males have spots on their wings, thus the name.

Oh yes, their size is 1/16th to 1/8 of an inch long, thus the importance of the six of the holes in the yogurt container.


The best first step is to prevent the future life cycles by keeping the area clean under the tree, clearing away any fallen fruit.

Don’t compost the fruit, but place it in plastic bags.

If the pest is in your neighborhood, it might be better not to plant cherries, berries and strawberries.

If you already have these plants, Bob suggested providing a protective layer of netting.

Harvesting the fruit early also reduces exposure to the pest, he said.

Chemical controls include Spinosad, an insecticide used to control olive fruit fly.

A Spinosad product is Monterey Garden Insect Spray, he advised,

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