What is the codling moth?
The codling moth – Cydia pomonella – can cause major damage to apples, pears and plums, and to a lesser degree to walnut, apricot, peach, cherry and chestnut. The moths appear when they hatch from pupae in late May-early June, and lay eggs on twigs near developing fruits. In one or two weeks the eggs hatch, and the codling moth caterpillars find a fruit, bore into it, and start to feed on the seeds. This halts the development of the fruit, which ripens prematurely and may fall from the tree. The caterpillar exits the fruit, descends the tree down the trunk if the fruit is still attached to the branch, and finds a place in ground vegetation in which to pupate.
How to treat codling moth
Good pruning can help control codling moth, because sunlight dries out the eggs and larvae, and so keeping the canopy open to light and air is useful. Orchard hygiene is also important: collect any fallen fruit and dispose of it definitively. A corrugated cardboard strip wrapped around the trunk is a method of trapping the larvae as they descend: they use the cardboard as a place in which to pupate. Small songbirds such as bluetits like eating small caterpillars and so are a great asset in a garden or orchard. Install the right sort of nest boxes in a suitable place near your fruit trees.