codling moths (13590 bytes)

Never Coddle a Codling Moth!

By Bill Cart, Colorado Master GardenerSM, Colorado State University Cooperative Extension, Denver County

Growing "home grown" apples and pears -- and storing them for later enjoyment -- can be one of gardening's most delectable rewards!

But without special care, you'll be sharing these delights with the proverbial "worm in the apple" -- the larvae of the codling moth, Cydia (Laspeyresia) pomonella. These "gorging gourmets" hatch soon after the developing fruit is about three-fourths inch in diameter (early-to-mid-June), burrow through the fruit skin into the flesh and gorge themselves for three to four weeks until they're fully grown. Then they eat out an exit hole and leave the fruit, ready to begin the cycle all over again (late July). Two generations a year are the norm, but egg hatch can extend over a lengthy period between and beyond these dates. Therefore, controls for them should extend over the entire summer following the first egg hatch.

codling moth larva in apple (17583 bytes)

Codling moth larva

For the most effective control, thoroughly spray your tree(s) shortly after petal fall and then every two weeks through the summer with permethrin or carbaryl. Never apply insecticides when the tree(s) are blooming, so as to avoid killing beneficial pollinators.  Thin the immature fruits to prevent them from touching. (Thinning assures complete spray coverage on the fruit and allows the remaining fruit to reach maximum size.)

For "organic" control (but less effectiveness), combine the following tactics:

  • Encircle the tree trunk(s) with corrugated cardboard that can be taken down easily and replaced, preferably weekly. The codling moth larvae and pupae that hide in it can be crushed in place.

  • Hang a "Tree Tavern" -- a wide-mouthed container of molasses and water in a 1:10 ratio -- in the tree(s) to trap the adult moth.

  • Use the botanical insecticide ryania frequently. It is effective, but is expensive and difficult to find (garden-supply mail-order catalogs usually).

Following a regular schedule of "codling control" can result in a truly "epicurean" harvest!


Photograph of adult codling moths courtesy of Jack Kelly Clark.

Photograph of codling moth larva courtesy of USDA ARS.

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Date last revised: 01/05/2010