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How do I keep the little white worms out of my cherries?

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The western cherry fruit fly adult is a small true fly with dark bands on its wings.  It over winters in soil under cherry trees and adults emerge the following spring from late May to early June in northern Utah.  Once the fruits take on a salmon to rosy blush in color they become soft enough for female fruit flies to penetrate the skin to lay eggs.  After the eggs develop under the skin, they hatch into white worms that feed on the flesh of fruits.  You find these small, white worms when you take a bite or remove the cherry pit.  Consuming fruit fly larvae is not harmful, but most Americans don’t prefer to have a little extra protein with their fruit.  Here are some tips on how to keep the worms out of your cherries:

  • Insecticides are the primary control for cherry fruit fly.  Begin protecting fruit when it turns salmon to rose in color.  It is most effective if all cherry trees in an area are treated to prevent flies from emigrating from infested sites.  Let your neighbors know and encourage them to spray to help keep the fruit fly populations down.  Effective insecticides for the homeowner include spinosad (Success or Entrust), permethrin, carbaryl (Sevin), methoxychlor, malathion, pyrethrum (Pyganic), endosulfan (Thiodan), and azadirachtin (Neem, Azatin).
  • For helpful cultural control, place plastic landscape fabric or another barrier on the ground under the canopy of cherry trees to prevent larvae in dropped fruit from burrowing into the soil where they will pupate for the winter.  Landscape fabric placed in the spring will also prevent adults from emerging from the soil.  Keep the fabric in place year-round and prevent a buildup of soil and debris on top that would provide pupation sites for the fruit fly.

Posted on 14 Sep 2006

Diane Alston
Hort-Entomologist Specialist

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