Codling Moth in Utah Orchards

• Size and Color:  1/2 inch long; mottled gray and brown moth; bands of alternating gray and white on wings with a bronze to copper spot on the tip of each forewing (Fig. 1).
• Where:  camouflaged against tree bark during the day with wings held tent-like over body.
• In spring, moths start emerging when evening temperatures exceed 55°F.  Each evening, peak moth activity is a few hours before and after twilight.
• Mated female moths can each lay 30 to 70 eggs.

Egg

• Shape and Color:  pinhead sized, flat, oval;  translucent when first deposited, later turning white; just before hatching, the black head of the larva is visible.
• Where:  laid singly on fruit or on leaves near fruit; difficult to spot (Fig. 2).
• Hatch occurs in 6 to 20 days, depending on temperature.

Larva (Damaging and Overwintering Stages)

• Size and Color:  1/10 inch long upon hatching, pale white with a black head; 1/2 - 3/4 inch long when fully grown, tan to pink with a brown head (Fig. 3).
• Where:  enter fruit within 24 hours after hatching, tunneling to core to feed on developing seeds.
• Larvae pass through five instars inside fruit in 3 to 5 weeks, after which they exit the fruit to seek out a protected site (under loose bark, at the base of the tree, in fruit bins, in orchard trash piles).

Pupa

• Size and Color:  1/2 inch long, brown.
• Where:  pupation of overwintering larvae occurs when spring temperatures exceed 50° F in late February and early March.
• The development period is 7 to 30 days, depending on temperature.

• Larvae tunnel to center of fruit to feed on seeds.
• Brown frass (excrement) extrudes from entry and exit holes (Fig. 5).
• Fruit attacked during the first generation drops prematurely.
• Entries often happen at the calyx end (Fig 5, left).

Stings

• Stings (Fig. 5, right) are healed shallow or aborted entries that occur due to larval death or when larvae abandon a feeding site.

TIMING CONTROL

Monitoring with Pheromone Traps

Trap Placement

• Large plastic delta traps with a pheromone lure placed atop a sticky liner can be used to monitor adult activity (Fig. 6). Orange traps should be used, as white traps attract bees. Click here for suppliers.
• Various types of lures are available. Sex pheromone lures (codlemone) attract male moths and pear ester (kairomone) attracts females. The addition of acetic acid to the lure enhances trap catch. Choice and strength of the lure will depend on whether the orchard will be treated with mating disruption.  Lures are available as a rubber septum or membrane: 

• Traps should be hung in orchards by first bloom or based on degree-day (temperature) accumulations (Table 1). Place them within the upper third of the tree canopy (preferably 6 - 7 ft. high), making sure the trap entrance is not blocked and that it is parallel to the prevailing wind direction (Fig. 7).
• A minimum of two traps should be placed in each orchard. For orchards greater than 10 acres, use one trap for every 5 acres.
• Hang at least one trap on the edge and at least one near the center of the orchard to determine if moths are immigrating from outside sources and/or over-wintering within the orchard. Suspected “hot spots” within the orchard should be monitored separately.

• Codling moth development occurs between the lower and upper thresholds of 50°F and 88°F.
• The development of codling moth, like all insects, can be predicted based on accumulated heat over time, called degree days (DD). Use of the codling moth DD model will help to more accurately time insecticide applications and optimize the number of total applications.
• Site-specific degree day information can be obtained from the Utah Climate Center TRAPs website or from your county Extension office.
• Place pheromone traps in orchards when 100 DD have accumulated (first pink of Red Delicious) after January 1 in southern Utah or after March 1 in northern Utah.  The first moths are expected by 150 - 200 DD (approximately full bloom of Red Delicious).
• Once biofix (first consistent moth catch) has occurred, the codling moth model begins (Table 1).

Timing Sprays

• If mating disruption (MD, see page 6) is used in an orchard, dispensers should be hung immediately before or at biofix to prevent mating and egg-laying (get a biofix at a nearby non-MD location or use site-specific fixed biofix date). Supplemental insecticide treatments are usually necessary even when MD is used. The first cover spray is critical for suppression of the first generation, and thus, the following generations.
• Apply the first cover spray for each generation as noted in Table 1. Reapply insecticides based on the protection interval of the product used. Keep fruit protected throughout each generation, and up through mid-September (when codling moth activity ends).
• If using mating disruption, apply insecticide according to trap catch (see next section).
• As harvest date approaches, consider the pre-harvest interval (required time interval between insecticide application and harvest) in planning late-season treatments.

MANAGEMENT

Fruit Thinning

Newly-hatched larvae often seek out protected sites for entry, such as where fruits touch each other.  Thinning fruit to just one apple per cluster can limit entries. Fruit thinning also allows for improved insecticide coverage on the entire fruits.

Sanitation

• Remove abandoned orchards and wild hosts within a quarter-mile (450 yards) of orchards to destroy outside codling moth sources.
• Strip fruit remaining after harvest in young, unharvested orchards or on pollinator trees.
• Remove or destroy nearby piles of culled fruit.
• Remove additional pupation sites from orchards such as fruit bins, brush, woodpiles, and other debris.
• Fruit infested during the first generation typically drop to the ground in June or July. Remove or destroy (e.g., flail or mow) dropped fruit to reduce second-generation densities.

Trunk Banding

• Place corrugated cardboard bands, burlap, or similar material (2 - 3 inches wide) around trunks of trees in May to collect first generation larvae, and repeat in August to collect overwintering larvae that are moving to the trunks to pupate.
• Remove and destroy the bands before moths emerge in mid- to late June (for first generation) or in late October to November (for overwintering generation).
• This method is most effective on smooth-barked trees and in smaller, isolated orchards without nearby sources of codling moth.

*Begin accumulating degree days after daily temperatures begin to exceed 50°F,  typically on January 1 for southern Utah or March 1 for northern Utah.

† Biofix is when at least one moth is caught on consecutive nights.

^RRestricted use products require an applicator license.