Codling Moth
(Cydia pomonella)

Full-grown codling moth larvae overwinter in thick silken cocoons under loose bark, in the soil, or within debris under infested trees. Overwintering codling moth can also survive in bin piles, ladders, poles, barns, and leftover pruning piles, leading to higher pest pressure in adjacent apple blocks. Sanitizing bins after harvest and burning pruning piles before spring can help suppress pest pressure. If using mating disruption, it is recommended to apply extra dispensers in orchard rows adjacent to these areas. For more information on mating disruption, see our article on application rates.

During the spring months, larvae pupate within their silken cocoons. Adult emergence is highly dependent on spring temperatures and can vary from state to state. Moths usually begin emerging in early May and continue to emerge until late June (mid-July in cooler areas). Use degree day models and nearby weather station data to estimate emergence and other developmental thresholds in your area (see degree day explanation for more information). Moths are active a few hours before and after sunset. Both mating and egg-laying occur when twilight temperatures are above 62°F. Female codling moth lay eggs on fruit, nuts, and leaves. Larvae usually wander over the fruit surface before cutting through the skin and boring deeply into the fruit. Codling moth larvae chew their way through their egg casings when emerging. Because of this behavior, virus applications may be used to cover codling moth eggs. The emerging larvae will ingest the virus and die shortly after emergence. Virus is not effective against the adult codling moth.

Mature larvae leave the fruit to pupate in protected sites on and off the tree as described above (again, make sure that any pruning piles are burnt during this time). The second generation emerges in late July and August (approximately 1,060 DD50 post BioFix). Because the weather during July and August is usually favorable for codling moth activity and reproduction, second-generation larvae can cause considerable damage to fruit if left unchecked. In America, codling moth can experience two, three, or four generations a year depending on the climate. Below is a general guideline for codling moth timing.