How to keep those worms out of your apples and pears

You might not know their names, but you’ve probably met codling moths before. Codling “moth” sounds kind of cute and fluttery; you’ve encountered it as the “worm” in your apple.

Yuck!

Messing with the life cycle of the codling moth

Codling moths are a serious pest for apple, pear and walnut trees. Control them by interrupting their life cycle at various points. Here’s a helpful diagram from UC Davis Integrated Pest Management that illustrates the life of a codling moth.

The egg hatches somewhere on a tree’s leaf or fruit, then the larva enters the fruit and grows. It exits the fruit to pupate in a cocoon on the ground, or in loose bark on the tree. Adult codling moths emerge to mate and lay eggs.

Stop the egg laying

Use codling moth traps to capture male moths before they can mate. Set the traps at bloom time, and hang them in the top third of your tree canopy (1 or 2 traps for a small tree, and 2 to 4 traps for a large tree). Some avid males are bound to have mated before they find the trap.

Depending on your climate, there can be several generations of codling moths each growing season. Replace the lures every 8 weeks, until you harvest your fruit and walnuts.

Make the larvae sick

Use the insecticidal virus CYD-X as a spray when the eggs are hatching. This virus will not harm beneficial insects and is listed by OMRI [Organic Materials Review Institute] as acceptable for use on organic farms.

The eggs hatch during certain temperatures and the UC Davis Integrated Pest Management site has a brand-new degree-day program you can use to determine hatching times in your orchard.

Stop the larvae from getting inside the fruit

A physical barrier will keep most of the larvae out of the fruit. Our maggot barriers are like small nylon stockings to slide on each fruit (the barrier expands as the fruit grows).

Stop the larvae from pupating over the winter

Once a larva climbs out of the fruit it will find a sheltered spot in loose bark on the tree, or in litter on the ground, and build a cocoon.

Capture the larva (now a caterpillar) as it descends, looking for a place to pupate, when you wrap “trunk bands” around the tree. Our Tanglefoot Sticky Tree Bands are ready to wrap.

Use the orchard sanitation techniques that Tricia discusses in our new video about codling moth control. In the spring—check fruit for entrance holes and discard any affected fruit; pick up and discard fallen fruit. In the fall—remove dead fruit from the tree; rake up and discard fruit and leaves.

In the large orchard

When you’re dealing with lots of fruit and nut trees, you’ll need more supplies:

* Confusion pheromone dispensers to hang in the trees— Isomate C+ or Isomate CTT

* Surround, a kaolin clay powder that acts as a surface barrier on all parts of the tree

* A large number of maggot barriers

* A large amount of CYD-X virus

Check with your county Cooperative Extension office to see if you need a permit to spray the CYD-X virus and the Surround kaolin clay powder.

For more information on codling moth control, see the UC Integrated Pest Management Pest Note on the Codling Moth.

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