Why Are My Pears Full of Maggots?

Finding a pink-white caterpillar tunnelling through the core of your pear is almost always codling moth. It is one of the most widespread pests of pears and apples in temperate regions, and a heavy infestation can ruin a significant proportion of the crop before you even know it is there. The damage is internal — you often cannot tell a fruit is infested until you cut it open or find the exit hole when the caterpillar has already left.

Understanding the codling moth lifecycle

Adult codling moths (Cydia pomonella) emerge in late May and early June. Females lay eggs singly on developing fruitlets or leaves nearby. The tiny newly hatched caterpillars bore into the fruitlet, usually through the eye end, tunnel to the core and feed on the seeds. A mature caterpillar exits through the side of the fruit, leaving a hole filled with brown frass, and crawls down to overwinter as a cocoon under loose bark or in debris around the base of the tree. There are typically one to two generations per year in temperate climates.

Pheromone traps

Hang codling moth pheromone traps in the tree from late May, following the manufacturer's instructions. The lure in the trap releases a synthetic version of the female moth's sex pheromone, attracting and trapping male moths. Monitor the trap weekly — the number of moths caught tells you how high the local population is and when peak flight is occurring. High trap catches in June indicate a significant infestation and the need for additional action.

Grease bands and sticky traps

Wrapping a grease band around the trunk in late summer catches caterpillars as they crawl down to find overwintering sites. While this alone will not prevent infestation, it reduces the population going into winter and therefore the number of moths emerging the following spring. Renew the band annually.

Removing and destroying fallen fruit

Fallen fruit contains larvae that have completed their feeding and are ready to pupate. Collecting and destroying windfalls every few days throughout summer — bagging them for the household waste rather than composting — removes these larvae from the site and significantly reduces the population for subsequent years. Do not leave fallen fruit rotting under the tree.