Codling Moth—You Can Limit the Damage It Causes

The codling moth is the most serious insect pest of apples, pears and walnuts. The larva eats its way into the fruit or nut. Although it doesn't destroy the fruit, it ruins the commercial quality, reducing the growers income. Larvae are also pests to crabapples and hawthorns.

Identifying the Moth, Larva and Eggs

The adult moth can be identified by its grayish brown with lacy brown lines on the forewings.

The larvae are pink with brown heads. They're larger than the adult, one inch for the larva to the adult's 3/4 inch.

There are 2 generations per year. The first generation larvae are present in fruit from June to late August.

The second generation larvae emerge in early August.

After mating, female moths will lay up to 20 eggs in a week's time. The eggs are flat, white, and laid singly.

They're laid directly on the fruit, or sometimes on leaves. The eggs takes one to three weeks to hatch depending on the temperature.

Photo courtesy of
Scott Bauer, Agricultural Research Service

According to the USDA Agricultural Research Service:

The luscious aroma of ripe pears could spell doom to these moths. Agricultural Research Service scientists have discovered that a certain chemical in pears provides just the right perfume to attract female codling moths to traps. That's a breakthrough that may revolutionize integrated pest management in apple, pear, and walnut orchards worldwide—and will help growers to continue providing safe food more economically.

They are the most severe and widely distributed pest of apples, pears, and walnuts in the world. The moths were accidentally introduced into the United States from Europe in the 1700s and have been a menace ever since.

Uncontrolled, the larvae—the worm in the apple—can destroy up to 95 percent of an apple crop and up to 60 percent of a pear crop. Feeding by larvae creates holes in walnut hulls and shells that can allow fungi to enter and infect the kernels. Some fungi produce toxins that at high levels are a food safety concern. Both federal and international regulations prohibit growers from selling toxin-contaminated nuts.

The damage is caused by the larva eating through the flesh as it tunnels toward the core to feed on the seeds. These injuries cause internal breakdown of the fruit, often leading to premature drop from the tree.

Codling moth control is done naturally by woodpeckers, ground beetles, braconid wasps and trichogramma wasps.

Pheromones (a chemical produced from pears) and pheromone traps have mostly eliminated the commercial orchard codling moth problem in North America. This organic control has been researched extensively by the USDA.

If this page was valuable for you, please share your new knowledge. Click Like...