Cherry fly, techniques & treatments to avoid its maggots

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A small brown patch shrivels on the skin, tiny pinholes squirt juice when pressed, and inside sits a little white maggot: the work of the cherry fruit fly (Rhagoletis cerasi in Europe), a 4 mm insect that hovers around ripening fruit. Once the maggot is in, the cherry is lost, so only prevention saves a harvest.

Generally, this happens end of May or beginning of June, and can last until July.

Refer to our guidance on how to effectively fight against cherry flies, and you’ll spare yourself the disappointment of seeing your cherry harvest ruined.

Symptoms of a cherry fruit fly invasion

From under the tree, it’s quite difficult to know whether the cherry fly is active or not. You’ll have to check on the cherries up close as soon as they start forming. Picking an infected one makes it easier to identify the pest.

• A small part of the cherry starts to turn brown and shrivels up.
• Tiny pinholes can be seen along the cherry’s skin and when pressed, juice squirts out through them.
• The fruit rots from the inside, and the cherry maggot hatched from laid eggs appears.

Sometimes, you only discover this little white maggot when you already took a bite from the cherry! Eww!

Which cherry tree cultivars are most hit?

Late-bearing cultivars are often harder hit than cultivars with early fruit fruit formation.

• Cherry cultivars ripen at different times, and many nurseries list a variety’s ripening season on its label or in catalogue descriptions; where that detail is missing, you can ask staff before buying.
• Sour cherries such as Morello and Griotte generally ripen later than sweet Bigarreau types, and late-ripening cherries are widely reported to be more exposed to cherry fruit fly egg-laying than early-ripening ones.

What does the cherry fly look like?

It’s a small fly that belongs to the Rhagoletis family. There are a number of variations that look very similar:

• Rhagoletis cingulata, the eastern cherry fruit fly, is found in central and eastern United States and Canada.
• Rhagoletis cerasi, the European cherry fruit fly, strikes only in Europe, including the United Kingdom.
• Rhagoletis fausta, the black cherry fruit fly, can be found in the entire United States and Southern Canada.
• Rhagoletis indifferens, the western cherry fruit fly, appears in the Western United States.

These all are about a quarter-inch (4 mm) in size and are hard to see on the trees. They hover in flight as they inspect cherries to lay their eggs in. The maggots start off tiny and nibble around the pit until they’re about 1/4th inch (4 mm) long.

Here’s a video that shows the cherry fruit fly

The control options compared

Once a maggot is inside a cherry the fruit is lost, so every option below works by stopping the eggs being laid in the first place.

Pairing an early cultivar with early picking leaves the fly the fewest opportunities of all.

Best way to treat against the fly

Once maggots are in a fruit, they ruin it. The only way to deal with it is to prevent their coming. Here are different ways to avoid or trap them:

• First of all, the most effective solution is to plant early varieties such as the ‘Bigarreau‘ variety, since the fruits mature before the fly has yet spread to become seriously invasive.
• Set up sulfate ammonium traps to attract the flies, also called pheromone traps.
• Spray a 100% organic selective insecticide.

→ See also:

• Cherry trees
• Fruit flies
• Fighting aphids
• Fighting caterpillars
• Fighting codling moth larvae