Codling Moth (Cydia pomonella)

Biology of codling moth

Adults

The spring flight of CM adults begins when apples are in late bloom. In New York, second and third flights begin in early to mid-July and mid-August, respectively. Frequently, the second and third flights overlap, resulting in the presence of adults from early July through the remainder of the growing season. CM adults are 10-12 mm (0.5 in.) long, with a wing span of 15 to 20 mm (0.75 in). The moths are an iridescent gray to brown color with a chocolate-brown patch, containing copper to gold markings, located at the tip of each forewing (figure 1a-b). The hind wings, which are not visible when the moth is at rest, are a lighter, copper-brown color. 

During the day, CM adults remain at rest, well camouflaged, on the bark of trees. If the temperature is above 10-15.5°C (50-60°F) at dusk, the moths become active, mate, and the females lay their eggs. Under similar conditions, the moths can also be active at dawn. A female may lay up to 100 eggs. 

Eggs

CM eggs are laid singly, generally on the upper surface of leaves, or on the fruit. The eggs are flat, oval discs measuring 1.0 by 1.25 mm (0.04 by 0.05 in.). When first laid, an egg is translucent. It later develops a reddish embryonic ring; this is called the "red ring stage" (figure 2). Shortly before hatching, the dark head capsule of the developing larva can be seen; this is called the "black head stage". Egg hatch occurs in 6-20 days depending on prevailing temperatures. First generation egg hatch begins at petal fall and continues for 2-3 weeks.

Larvae

CM larvae go through 5 instars in 3-5 weeks. At egg hatch, larvae are about 2 mm (0.08 in.) long and white with a black head and thoracic and anal shields. Larvae are 13-19 mm (0.5-0. 75 in.) long when fully grown. The body is pinkish white, while the head and thoracic and anal shields are brown (figure 3).

Newly hatched larvae seek fruit, which they enter to feed and develop. Entry may be through the calyx or the opposite side of the fruit. Larvae discard their first bites of epidermis, then either feed beneath the surface or tunnel directly to the center of the fruit. CM larvae deliberately feed on the seeds of the fruit. As larval development nears completion, they eat out an exit tunnel, which they plug with frass (figure 4).

Larvae leave the fruit and construct a thick silken cocoon under loose bark or in some other protected spot. The cocoon serves as a hibernaculum for the overwintering larva.

Pupae

CM pupae are about 13 mm (0.5 in.) long and brown. The pupal period ranges from 7-30 days, depending on temperatures.

Damage of codling moth

CM larvae are fruit feeders and cause little or no injury to other plant parts. A larva may take a bite or two of a fruit causing an injury known as a "sting". Or, it may continue feeding, producing a deep entry into the fruit (figure 5). A "sting" causes a surface blemish , but unlike a deep entry, it does not result in interior breakdown of the fruit. Fruit with "stings" from the first generation usually remain on the tree, while those with deep entries usually fall during the "June drop." Subsequent generations may or may not cause premature drop, depending on the variety. Second generation larvae are active in fruit throughout August. This later, deep entry damage is a more significant problem because affected fruit must be culled. Failure to cull may downgrade a load.

Codling moth management

Predators and parasites feed on CM, but these natural enemies cannot keep this pest from reaching damaging levels in commercial orchards. 

Mating disruption

For growers planning to use mating disruption as part of their annual codling moth (CM) management program, there are a number of several products on the market that affect both codling moth and the oriental fruit moth (OFM) simultaneously, in addition to a number of products that affect just a single species. If your target is both CM and OFM, there are a number of products that affect both pests –some product options include CheckMate CM/OFM Puffer, Isomate CM/OFM TT, Cidetrak CM-OFM Combo, and Isomate CM/OFM Mist Plus. 

Among products that target a single species, there is Cidetrak CMDA Combo Meso. Please follow the label for each product for dispenser density and placement within the tree (for CM, place the dispensers in the top 20-30 percent of the tree canopy). 

For those growers who have used a mating disruption product for CM in previous years, it is likely that you will need some supplemental insecticides, especially for the first generation (see below for a listing of product choices). In addition, it is very important that you place pheromone traps in trees to monitor the success of your mating disruption program. We have conducted a number of studies with a newer lure from Trécé Inc. to monitor CM in mating disruption blocks, called a CM-DA Combo. It contains both the sex pheromone – which is released by the females to attract the males – and a kairomone (i.e., a plant-derived chemical volatile [i.e., pear ester]) that attracts both male and female moths. We recommend at least one trap per 5 acres with no less than one trap per 10 acres to determine the success of your mating disruption program. There are also powerful 10X lures available for monitoring CM male adults in mating disruption blocks. These lures allow you to monitor the activity of the moths in the “background” while the mating disruption is still working. Catching moths in traps with a 1X lure would indicate mating disruption is not working.

Conventional management

If your plan is to use just conventional insecticides for CM control, your choice of products is quite varied, depending on the stage of CM you wish to target. Products that possess ovicidal activity (i.e., affecting the eggs) should be applied as follows: Intrepid or Rimon – apply within 150–175 DD after biofix and follow up 14 days later (note, Rimon may only be used once per season in NYS). Insecticides that target the hatching larvae (i.e., 230–250 DD after biofix) are as follows: diamides (e.g., Altacor, Exirel, Verdepryn, Besiege, Voliam Flexi), organophosphates (Imidan), neonicotinoids (e.g., Assail), indoxacarb (e.g. Avaunt), spinetoram (e.g. Delegate), and Chromobacterium subtsugae (e.g.Grandevo).  Please refer to the Tree Fruit Pest Management Guidelines for rates on these products. It is important to implement good resistance management practices for all of the above products; that is, use only one of the abovethe same active ingredient for each of multiple sprayss within the same generation of CM; do not use the same active ingredients across two consecutive generations).

Biologicals

Another option that growers can consider for CM control is a codling moth granulosis virus (CpGV) (e.g., Cyd-X, Virosoft or Madex HP, the latter two containing a CpGV that is active on both CM and OFM). These products can be used very successfully in combination with mating disruption to reduce the severity of this pest. CpGV products must be ingested by the hatching larvae. The larvae will continue to feed for a couple of days before the virus kills them. CpGV products are fairly short residual (i.e., 5–7 days); thus, they need to be reapplied more often than conventional insecticides. Growers will likely need 4–5 applications per generation depending on the length of the egg hatch period, the severity of the populations, and weather conditions.

Guide to codling moth stages

• Adults first flight
  Timing: Bloom through 30 days past petal fall 
  Where to look: Pheromone traps
• Adults second flight
  Timing: 30 days past petal fall through harvest
  Where to look: Pheromone traps
• Eggs
  Timing: Bloom through harvest 
  Where to look: Upper leaf surface and fruit
• Larvae
  Timing: Petal fall through harvest
  Where to look: In the fruit
• Overwintering larvae
  Timing: August through tight cluster
  Where to look: In cocoons under bark on trunk or lower scaffolds
• Pupae
  Timing: Half-inch green through one week past petal fall
  Where to look: In cocoons under bark on trunk or lower scaffolds