Codling Moth: Maggots in Your Apples

Cut open a windfall apple and find a brown tunnel with a fat little maggot at the end? That is codling moth. The caterpillars bore into the fruit through a small hole near the eye or side, eat their way to the core, and leave behind the crumbly brown mess every UK apple grower knows. Pears get hit too. There is no saving an affected apple — but you can protect next year's crop.

The life cycle

Knowing the timing is half the battle.

• Late May to July: the adult moth flies on warm, still evenings (above roughly 15°C) and lays tiny eggs on developing fruit and nearby leaves.
• Early to mid summer: the eggs hatch and the pinkish-white caterpillars tunnel straight into the young fruit, heading for the pips.
• Late summer: when fully fed, each caterpillar chews its way out, drops down or crawls to the trunk, and spins a cocoon under loose bark, in cracks or in leaf litter.
• Overwinter: it sits tight as a cocoon through winter and pupates in spring, ready to start again. In a warm UK summer you can get a partial second generation, which is why early control matters.

The hole you see in a picked apple is usually the exit hole, ringed with reddish-brown frass (that crumbly waste). By then the damage is done.

Organic control

You will not eradicate codling moth, but you can knock numbers right down without spraying.

Hang pheromone traps from late May. This is the single most useful thing you can do. The trap is a small open tent with a sticky base and a pheromone lure that mimics the female's scent, so it catches the males. On a small tree or two it genuinely reduces the next generation; on any size of tree it tells you when the moths are flying, so you can time other action. One trap covers roughly five trees — hang it at head height by late May and check it through summer.

Encourage birds. Blue tits and great tits hunt overwintering caterpillars out of bark crevices all winter long. Putting up nest boxes and keeping the garden bird-friendly turns your tits into a free pest patrol. A broader wildlife-friendly garden supports the predators and parasitic wasps that keep many orchard pests in check.

Fit grease bands or corrugated cardboard traps. Wrap a band of sacking or corrugated cardboard around the trunk in mid-summer. Fully fed caterpillars looking for somewhere to pupate crawl in — then you peel it off in autumn and burn or bin it, taking that batch out of the cycle.

Clear fallen fruit promptly. Windfalls often contain a live caterpillar still inside. Pick up dropped apples every few days through late summer and either use them straight away or get rid of them, rather than leaving a buffet of next year's moths under the tree.

If you want to back the traps up, a kit makes it painless to get the timing right.

What you cannot do

Once a caterpillar is inside the apple, there is no rescue. No spray, feed or trick will tunnel in after it, and a maggoty apple will not heal over or ripen properly. Don't waste effort trying to save individual fruit.

The practical move is to cut out the damaged part, use what is sound (the rest of the apple is fine to eat or cook), and make sure the windfall doesn't sit on the ground releasing another moth. Everything you do this season is about protecting next year's crop, not this fruit.

Prevention next year

Codling moth is a numbers game — each thing you do shaves the population down for the following summer.

• Trap early, every year. Get the pheromone trap up by late May without fail. Consistent trapping over a few seasons makes a real difference on a small tree.
• Keep the birds onside. Leave the nest boxes up, feed birds over winter, and resist tidying every scrap of loose bark — that is where the tits do their hunting.
• Practise good hygiene. Clear fallen fruit, scrape off obviously loose flaking bark on older trees in winter, and remove and destroy any cardboard or grease bands you put on, with their cargo of caterpillars.
• Don't panic over a few. A handful of grubby apples on an otherwise healthy tree is normal and nothing to spray for. Many UK gardeners simply accept a small share to the moth and cut around it.

For everything else about growing and looking after your trees — from choosing a tree to feeding, watering and the wider common apple problems — head back to the main apple guide. You'll also find more troubleshooters over in the problem-solving section.

PS — if you can only do one thing, it's the pheromone trap up by late May. Cheap, no spraying, and it pays you back next harvest.