Codling Moth Lifecycle

Because control measures generally target a specific stage (or stages) in the codling moth's life cycle, understanding the life cycle is fundamental to any control program. 

Below is a representation of the codling moth life cycle.

Mature codling moth larvae spend the winter in cocoons located in protected sites on the tree (e.g. under loose bark and in cracks and crevices), in the soil, or in wooden materials under or beside infested trees (e.g. bins, ladders, poles, buildings, and large prunings).  

Control options at this stage are limited.  Scraping loose bark off of host trees, and cleaning up debris from around the tree can reduce the number of available cocoon sites.

Larvae pupate in the spring.  Adults usually begin to emerge in early May and continue to emerge until late June (mid-July in cooler areas), depending on temperature. 

As with the cocoon stage, control options in the pupa stage are limited to manual measures such as reducing available cocooning/pupating sites.

Mating and egg laying occur when twilight temperatures are above 15C.  Females lay eggs on the fruit or on leaves near the fruit.  Codling moth eggs are tiny (the size of a pin head) and difficult to see. 

This stage is the time at which the SIR Program's releases of sterile codling moths interrupts the moth's life cycle.  Another method that provides some control at the mating stage is mating disruption, though this method is not suitable for urban host trees. 

Some chemical pesticides and some horticultural oils can provide some control at the egg stage.

Larvae usually wander over the fruit surface before cutting through the skin and boring deeply into the fruit.  It is this stage (young larvae, before they enter the fruit) that is targeted by most chemical pesticides.

Mature larvae leave the fruit to form cocoons in protected sites on and off the tree.  The use of cardboard banding on host trees can serve to capture codling moth larvae during this stage.

Some of the cocooned larvae will overwinter (diapause) at this stage, to emerge as adult moths the following spring (some will even remain in diapause for an extra year or two).  Others will re-emerge as second-generation moths later in the same summer.

Second generation moths appear in late July and August.  Because weather during July and August is usually favourable for codling moth activity and reproduction, second-generation larvae can cause considerable damage, often close to harvest.

If weather is warm during late August or early September a partial third generation may occur in southern districts.