Codling Moth Identification

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Detection of codling moth
Detection of codling moth in the orchard   |  an online poster presentation
Codling moth AGWEST Farmnote

What you should know about codling moth

Codling moth, Cydia pomonella (Linnaeus) is found in all the world's major apple and pear growing areas, except Japan and Western Australia. Because of the damage it would certainly cause to the local fruit industry, it is illegal to bring live codling moth or infested fruit into Western Australia. It is "declared" by the Agriculture Protection Board. The absence of the codling moth in Western Australia gives our fruit growers a tremendous advantage over other states because we can market low-pesticide, pest-free fruit.

The discovery of codling moth at Bridgetown on 31 January 1993 and at Kalgan River (north-east of Albany) on 14 April 1993 were the eighteenth and nineteenth occasions respectively that an outbreak and subsequent eradication of this pest has occurred in WA. These infestations were the first in WA since the 1956 outbreak at Bridgetown. Without eradication the industry would have been exposed to an extra two million dollars per annum in spraying costs and production losses.

Adult codling moth.
Large photograph of moth by C. Bower (NSW Agriculture), insert moth photo by R. Knox (Agriculture Western Australia).

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Why codling moth matters to Western Australian fruit growers
Codling moth is the most damaging insect pest of apples and pears. It can tunnel into every single fruit on a tree. Damaged fruit may fall prematurely and no one wants to buy fruit with tunnels filled with larval excreta (frass). To minimise codling moth damage, growers in other Australian states have to spray up to 10 times each season with broad spectrum insecticides. These chemicals kill beneficial insects, increase the amount of pesticide in the environment and cost growers dearly in both time and money. The use of insecticides to control the codling moth has also resulted in secondary pest problems, particularly with the two-spotted mite, Tetranychus urticae Koch. Codling moths prefer apples, but they will also attack pears, nashi, quince and crab apples (the pome fruits). They have attacked stone fruit overseas, but this has not yet been seen in Australia. On occasions they will also attack walnuts.
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What you should look for?
 
Codling moth larva, with frass near apple exit hole.
Photo by R. Knox (Agriculture Western Australia).
Codling moth larval tunnel with apple showing chewed seeds and exit hole.
Photo by R. Knox (Agriculture Western Australia).

Adult moths are dull brown and about 10 mm long (see above). They have a dark patch with metallic bronze markings at the end of each wing. You will rarely see any eggs which are small (1 mm), round and flattened. Larvae are less than two mm long when they hatch, but up to 20 mm long when fully grown. You can tell if fruit contain codling moth larvae by the abundant frass seen on the outside of the fruit (see below). Cocoons are tough, white and stick firmly to the bark of the fruit tree. Pupae are dark, orange-brown and about 10 mm long (see below).

Codling moth pupa extracted from under bark.
Photo by R. Knox (Agriculture Western Australia)

 
Why codling moth would become a major pest in Western Australia
Codling moth is ideally suited to our climate (see below) and would have three generations every year in Western Australia, allowing large population to quickly develop.
  • Generation 1: The larvae over-winter cocooned in cracks and under bark of infested trees. They pupate in early spring; emerge in October and November, mate and lay eggs on the surface of small developing fruit. The larvae hatch out and burrow into the fruit to reach the core where they eat the seeds. As the fruits develop so do the moth larvae. By December the first larvae have reached full size. They drop to the ground on a silken thread and crawl to the trunk. There they spin a cocoon and pupate under the bark.
  • Generation 2: Moths emerge in December and January, mate and lay eggs on fruit. The larvae bore into the fruit, feed, leave, and pupate in the same way.
  • Generation 3: Moths emerge in February and March, repeating the process yet again. However the resulting larvae spin cocoons and over-winter in them. They pupate the following spring.
Climex prediction for the likely distribution of codling moth in Western Australia in irrigated orchards. The model assumes 40mm of irrigation per week over the summer period.

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Early warnings
Codling moths fly at dusk, but only from October to April. Male moths are attracted to females by a strong scent (pheromone). Traps give early warning of the presence of codling moth. They attract moths by synthetic pheromones, released from tiny rubber plugs. They catch moths on a sticky inside surface. Traps are effective in catching male codling moths from October to April. Site them in apple or pear orchards and replace them every month. Pheromone traps give early warning of codling moth infestations and allow Agriculture Western Australia to carry out cost-effective eradication programs. Pome fruit growers can obtain a sentinel codling moth trap from Agriculture Western Australia and help in the monitoring process for this pest.
Trap used by orchardists and by Agriculture Western Australia to detect codling moth incursions.
Photo by R. Knox (Agriculture Western Australia).

 
What do you do if you find infested fruit
If you find an apple or other pome fruit with a frass-filled tunnel reaching into the core, take it to the nearest Agriculture Western Australia office for identification. Other pests, such as the light brown apple moth, egg plant caterpillar and fruit fly can cause damage similar to codling moth, but these insects do not tunnel to the core and eat the seeds. Most important, do not bring fruit into Western Australia from other states or from overseas. Declare any fruit in your possession at the check- point or dispose of it at the airport in the bins provided.

 

 

Authors: Bill Woods & Darryl Hardie