How to Deal with Codling Moth Infestations

Photo courtesy of Amy Loves Yah at Flickr.com.

Codling moths are innocuous little flying bugs just a few millimeters across, and don’t seem too harmful at first glance — but their larvae are the classical worms in the apple, an agricultural pest known to and sworn at by every orchardist in the country (if not much of the world). A European immigrant, the larvae will happily chew up and destroy the innards of not just apples, but also walnuts, pears, and other tree crops. Control is generally by means of chemical pesticides, with a synthetic hormone derived from the female moth being the most effective.

As is often the case, the options are more limited for the organic gardener, but they do exist. Recent tests of kaolin-based sprays seem positive, as codling moths not only consider clay-covered leaves and fruits bad places to lay their eggs, they often don’t recognize them as habitat. However, this method is of limited effectiveness unless the entire tree is sprayed. This can be time consuming, but the clay usually wears off by harvest time if the tree is sprayed early in the season.

You can also defeat codling moth larvae by introducing trichogramma wasps into the environment; these tiny wasps lay their eggs in the codling moth eggs, and the wasp larvae eat the caterpillar embryos. This is the only known effective method of biological pest control for codling moths, since the larvae are generally protected within the fruit as they develop.

Finally, you can try “trunk banding,” which involves wrapping a piece of corrugated cardboard around the tree trunk. After stuffing themselves on fruit for about three weeks, the larvae will climb down the tree trunk and use the corrugation bands as pupation sites. In late October, you can remove the cardboard and burn it. While this may seem like a case of too little too late, it’ll certainly limit the next year’s local population of codling moths.