Codling moth can be treated organically

One of the most frustrating experiences for home orchardists is to have their crop of apples or pears compromised by an infestation of worms.

The worms are the immature larvae of codling moth (Cydia pomonella). Fruit growers eager to eliminate worms in apples must understand development of the insect and methods to keep them from damaging fruit. While chemical controls are effective, we'll focus on ways to keep fruit worm-free in a less toxic manner.

In early spring, the moths emerge about the time fruit trees are in full bloom. The adult moths lay tiny, pinhead-sized eggs after dusk, usually on leaves, once the sunset temperature is 68°F or higher. The eggs hatch in about 10 days. The tiny caterpillars may feed for a while on leaves before moving into the fruit. The caterpillar chews its way into the fruit core, where it feeds for three to five weeks. When it leaves the fruit and moves down the trunk and branches it searches for a suitable place to spin a cocoon. This might be under loose bark, in a crevice or in the ground. As autumn cools, the last larvae do not pupate, but remain in their cocoons to over-winter.

The most important natural enemy of the codling moth is the Trichogramma micro wasp, which eats the moth eggs. One female wasp is able to parasitize over 50 moth eggs. The adult micro-wasp feeds on insect eggs, nectar and pollen. As I wrote last week, growing suitable plants under the fruit trees as a pollen and nectar source helps to maintain a population of these beneficial insects. Favored plants include clover, buckwheat, mustard, Queen Anne's lace, alyssum, dill, coriander and cosmos. Other natural enemies of codling moth include tachinid flies, ichneumon wasps, braconid wasps, chalcid wasps, and carabid beetles. Spiders will eat codling moth eggs, moths and larvae.

Inspect your trees every week. Collect any fruit you find with small holes and destroy it. It makes excellent chicken food. In fact, a small flock of banty hens can be a fruit grower's best friend.

Large-pore, corrugated cardboard bands can be placed around trunks and limbs to trap caterpillars looking for a place to pupate. Inspect every three weeks and destroy any cocooned caterpillars. Keep these bands in place all year.

Open-mouthed jars can be filled with a variety of baits to attract codling moth. Try molasses diluted with water (1 part molasses to 9 parts water), fermenting apple juice, port or oil of cloves. Add a film of vegetable oil to stop moths from escaping and prevent mosquitoes breeding. Hang them in trees in the warmest part of the orchard to catch the earliest arrivals. Studies have shown codling moth prefer a bait four to five days old. Replace the baits every two weeks.

A good choice for the home gardener with only a few apple trees is to bag the fruit. Commercial exclusion bags are available in either waxed paper with a built-in twist tie or cloth with a drawstring. Bags should be placed over the fruit while it is very small. Bags should be removed four to five days before harvesting to allow the fruit to develop a stronger color. A big advantage to exclusion is it usually helps deal with bird and possum problems, as well.

"Desire" codling moth traps are a new generation codling moth trap that attracts both male and female moths for the whole season. They are used to monitor the mating activity of codling moth and will significantly help in control. They allow you to be aware of when codling moths become active and correctly time your control program.

A horticultural glue, such as Tanglefoot Glue, applied around the trunk of the tree will prevent the movement of some of the female moths from the ground into the tree. It should be in place from the first moth sighting until mid-winter. Using the glue below the corrugated cardboard bands will help to force the larvae looking for a pupation site into the cardboard bands.

By combining all of the above methods into a comprehensive control strategy, the home fruit grower can lessen, or eliminate entirely, the need for harsh chemical control of these pesky pests.

Stan Mapolski, aka The Rogue Gardener, can be heard from 9-10 a.m. Saturday mornings on KMED 1440 AM and seen in periodic gardening segments for KTVL Channel 10 News. Reach him at

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