Codling Moth
Garden pest · Cydia pomonella
Description
Codling moth is a pest of apples, pears, quince, and walnuts. Its caterpillars feed inside developing fruit or nuts, making tunnels and leaving brown, crumbly droppings called frass. Affected apples and pears may fall early or develop decay around the feeding site. The adult is a small, mottled gray-brown moth that is most active around dusk; its wingspan is about 15–20 mm. Newly hatched larvae are pale, becoming pinkish with a brown head as they grow. A larva usually enters fruit soon after hatching, where it is sheltered from sprays. Mature larvae leave the fruit and spin cocoons in protected places, including bark crevices and nearby debris. Depending on the climate, codling moth may produce one or several generations in a growing season. Damage can be easy to miss until fruit is cut open, so early monitoring matters.
Symptoms
- Rotting fruit
- Insects visible on the plant
How to Identify
Look for a small entry or exit hole in fruit, often surrounded by brown frass. Cutting open an affected apple or pear may reveal a tunnel toward the core and a pale or pinkish caterpillar with a brown head. Some fruit develops secondary rot or drops early. Codling moth differs from apple maggot: apple maggot larvae are legless, lack a distinct brown head, and make winding tunnels through the flesh rather than typically feeding toward the core. Pheromone traps can confirm that adult male codling moths are present, but a trap catch alone does not show how much fruit has been damaged.
Prevention
Inspect developing fruit regularly and promptly collect fallen and visibly infested fruit; dispose of it so larvae cannot escape and complete their life cycle. Thin fruit clusters so the remaining fruit does not touch, reducing sheltered entry points. For a small tree, bag individual fruit after pollination and thinning, before larvae enter, or use fine insect-exclusion netting after flowering. Check that coverings are secure and do not trap moths inside. Keep nearby host trees in mind: moths can move in from untreated trees. Pheromone traps help track adult activity and the timing of egg hatch. Mating disruption can reduce reproduction in larger, consistently treated orchard blocks, but is often less reliable for a single backyard tree.
Treatment
Start by removing infested fruit from the tree and ground throughout the season. Bag sound fruit where practical; bagging will not save fruit that already contains larvae. If monitoring shows moth activity, codling moth granulovirus (CpGV), where available and labeled for the crop, is a targeted treatment for newly hatched larvae. Apply it according to the label and repeat as directed, since larvae become difficult to reach once inside fruit. Other labeled options may include spinosad or insecticides recommended by a local extension service. Time any spray to egg hatch using trap catches and local guidance, rather than spraying after holes appear. Follow the product label, avoid spraying open flowers, and take precautions for bees and other beneficial insects; spinosad is hazardous to bees while wet. In a heavily affected planting, combine well-timed treatment with fruit removal and next season’s monitoring rather than relying on a single spray.
Plants Affected
Not sure this is your problem? Try the problem diagnoser.