Codling Moth Control
Description: Found in all apple-growing areas of the world, the codling moth (Cydia pomonella) is considered to be one of the most destructive pests of apples. Adults are gray to brown moths with a 3/4 inch wingspan. They have a chocolate-colored patch at the tip of each forewing and coppery transverse markings.
Codling moth larvae are pink or creamy white caterpillars with mottled brown heads that tunnel through apples directly to the core. As they feed, they push out mounds of fecal material, called frass, which gathers around the entrance hole. Damage lowers the market value of the fruit and makes it unfit for human consumption. Alternate host plants include pears, crabapples, walnuts and stone fruits.
Note: The codling moth was introduced to North America by the colonists more than 200 years ago and is now one of the leading pests in home orchards.
Life Cycle: Full grown larvae pass the winter in a cocoon beneath loose bark or in orchard litter. Pupation takes place in the spring. Moths begin emerging about the time that apple trees are in bloom and lay an average of 50 to 60 eggs on leaves, twigs and fruits. Once eggs hatch the larvae feed briefly on leaves, then damage fruit by boring into the centers. Larvae feed for three weeks, then leave to seek a suitable place to spin cocoons. There are two generations per year.
Control: Scrape loose bark in early spring to remove overwintering cocoon, and then spray horticultural oil. Beneficial nematodes may be applied to tree trunks in the spring, summer and fall to attack pupae. Use pheromone traps to determine main flight period for moths, then release trichogramma wasps to attack eggs. Pheromone traps will also help reduce male moths where populations are low and trees are isolated. Kaolin clay will suppress a broad range of apple pests and has shown over 90% control of codling moth. In areas of severe infestation, spray botanical insecticides when 75% of petals have fallen, followed by three sprays at 1-2 week intervals.
Note: Bt-kurstaki and spinosad sprays are moderately effective, since the larvae spend so little time feeding outside the fruit. Apply during egg hatching only (consult with a local extension agent for exact times).
Tip: In spring, band tree trunks tightly with corrugated cardboard strips (4-6 inches wide) to provide a site for the larvae to spin their cocoons. Remove and destroy the strips after cocoons are formed.
Photo Credit: Encyclopedia of New Zealand