Codling Moth

Latest Update 21st August 2016.

Codling Moth               
  • Codling moths are a major pest on apple trees and morph from the larval phase of their life cycle in leaf litter under the tree’s canopy, or in crevices in the tree’s bark.  They climb the tree or flutter upwards from branch to branch (they are poor flyers) to mate in the foliage.  The females lay their eggs on leaves or directly on the fruit.
  • The tiny larvae find an apple and start to burrow deep into the flesh.
  • I spray the foliage and young fruit in spring with organic horticultural oil.  It smothers larvae and eggs before they can infest the fruit.
  • Binomial name:                                 Cydia Pomonella. 
  • Family:                                             Tortricidae.
Why Codling Moths are a Pest. 
  • Codling moth larvae penetrate apples and pears and eat their way towards the centre.  They don't destroy the fruit, but the frass (excretia) contains toxic materials, and this can ruin a crop.
  • Codling moth is very difficult to control because once its larvae penetrate an apple or pear, they are protected against spraying.
  • Once the larvae are fully mature they leave the fruit and drop from the trees or climb down to search out pupation sites and continue the life cycle in the soil or on debris under the tree.  Some crawl back up the tree to pupate in bark crevices.  They pupate in cocoons during winter and in spring emerge as moths.
  • The moths are only active for a few hours around sunset, and the temperature at sunset must be higher than 17°C before they will mate.  After mating each female deposits 30 to 70 tiny eggs singly on fruit, leaves, or spurs.  After the eggs hatch, the young larvae seek out and bore into the nearest apple.
Organic Pest Control. 
  • Clear all debris from under the tree in winter.  Dispose of the debris by burying it 500mm under soil which is unlikely to be disturbed for some time, or cook it in a thermal compost pile.  
  • In spring before the apple blossom opens, spray the ground under your apple tree's canopy, and its trunk and branches, with organic horticultural oil to smother the larvae before they morph into moths.
  • At the same time apply masking tape to the trunk of the tree about 100mm above the ground and apply a ring of horticultural glue to stop the adult female moth from crawling up the tree to mate and lay eggs.  The masking tape protects the tree from the glue, and makes it easy to replace when it gets covered with dust or dead insects. 
  • As a final precaution, once the fruit sets and the plant comes into leaf, spray the foliage and fruit with more of the organic horticultural oil to smother any eggs which may have got through your defences.
  • Thin the fruit in late spring when it has set.  Check it at least twice a week looking for the first “stings,” or tiny mounds of reddish-brown frass (excreta) about 2mm in diameter.  If you scrape the frass away you can see the tiny entry hole where the newly hatched larva has just entered the fruit.  The affected fruit must be removed and placed in sealable plastic bags.  They should then be cooked in the sun to kill the larvae.  
  • Don’t put the contaminated fruit in the compost without killing the larvae first.   Place cotton or paper exclusion bags over the remaining fruit.  The bags must have an effective sealing system.
  • Spray the foliage with aerated compost tea every month during the growing season.  This increases the plant's resistance to disease and pests by toughening up its foliage.