Western Cherry Fruit Fly Info – Controlling Western Cherry Fruit Flies

By Mary H. Dyer, Master Naturalist and Master Gardener

Western cherry fruit files are small pests, but they do big damage in home gardens and commercial orchards across the western United States. Read on for more western cherry fruit fly information.

Western Cherry Fruit Fly Identification

Western cherry fruit flies live in the soil as brownish-yellow pupae during the winter months, emerging as adult flies in late spring and early summer. Adult western cherry fruit flies are smaller than house flies, with black bodies marked with white bands. The flies are weak fliers and usually land on the nearest cherry tree.

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Female western cherry fruit flies, which fatten up on aphid honeydew and pollen, are ready to lay eggs about a week after emerging from the soil. Females live 35 days or less, but this relatively short period of time is long enough to do serious damage, which the pests accomplish by poking holes and laying eggs inside cherries.

One female can lay 50 to 200 eggs, which hatch maggot-like larvae in five to eight days. The larvae burrow deep into the cherry where they feed and grow for 10 to 12 days before falling to the ground, where the cherry fruit fly life cycle begins again.

Western Cherry Fruit Fly Control

In home gardens, fine netting can prevent adult fruit flies from landing on ripening fruit. Drape the netting over the tree and secure it with string or tape. Leave the netting in place until you’re ready to harvest the cherries.

While netting is effective for single trees, insecticides may be the best way of controlling western cherry fruit flies in orchards. The key to using insecticides effectively is timing. Many orchardists use baited sticky traps that reveal when adult flies are active – usually in mid-spring, when cherries are light green.

Several insecticides have proven to be effective in cherry fruit fly control, including spinosad, carbaryl, malathion and permethrin. Contact your local Cooperative Extension Office for specific info for controlling western cherry fruit flies in your area, as timing is critical. Use insecticides with care, as improper use may kill beneficial insects, including honeybees.

Preventing and Controlling Western Cherry Fruit Flies

Here are some tips that can help with prevention and control of these pests:

  • A thick layer of mulch on the ground around cherry trees may prevent the pests from burrowing into the soil, thus limiting new hatches.
  • Avoid leaving cherries on the trees at the end of the season to ensure the removal of all pest-infested fruit. If necessary, prune trees so you can easily reach the fruit. Similarly, pick up all fruit that drops on the ground. Insecticides may be needed to control late-emerging flies.
  • Parasitic wasps – especially braconid wasps – can help control the pests in home gardens, but usually aren’t effective in orchards.

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