Codling moth
Cydia pomonella
Its caterpillars tunnel to the core of apples and pears, leaving frass-filled exit holes. Hang pheromone traps from late spring and pick up windfalls promptly.
How to know it
The moth is small, gray and mottled with a coppery patch at the wingtip, and flies at dusk in early summer. What you find is the caterpillar: pinkish-white with a brown head, in a tunnel running to the core, and a hole plugged with wet brown frass.
What you'll see
- A single hole in the side or the eye of the fruit, ringed with crumbly brown frass.
- A brown tunnel driven to the core, with the seeds eaten and the cavity fouled.
- Fruit ripening and dropping early, small and misshapen.
- Pinkish caterpillars found when apples are cut at harvest.
- Damage discovered only in store, in fruit that looked sound when picked.
Where it comes from
Overwinters as a full-grown caterpillar in a silk cocoon under loose bark, in crevices and in store sheds. Moths fly from late May to July, laying single eggs near young fruit; the caterpillars enter within days, feed for a month, then leave the fruit to spin up. A second generation follows in a warm summer.
Warm, still evenings in June and July — the moths need calm weather above about 15 °C to fly and mate, so a cold wet early summer is a good apple year.
Dealing with it
- Hang pheromone traps from mid-May, one per few trees: they catch males, and more usefully they tell you exactly when the flight is on.
- Tie corrugated cardboard bands around the trunks in midsummer to catch the caterpillars spinning up, and burn the bands in winter.
- Collect and destroy windfalls and infested fruit promptly rather than leaving them under the tree.
- Encourage blue tits with nest boxes — they hunt overwintering cocoons out of the bark all winter.
- Apply codling-moth nematodes to the trunk and main branches in autumn on a damp mild evening.
Keeping it out
- Scrape loose bark and clear crevices on old trees in winter, where the cocoons sit.
- Keep the orchard floor clear of fallen fruit through the whole season.
- Grease-band and inspect trunks; the same bands catch winter moth as well.
- Store fruit in clean, sealed crates and check them, since caterpillars pupate in store.
- Grow a few early varieties, which are often picked before the second generation lands.
What it goes for
Apples above all, plus pears, quinces and occasionally walnuts.
Trouble it brings with it
Who hunts it for you
- BatsChiroptera A single bat takes hundreds of moths and mosquitoes in a night, and the moths are the parents of your cutworms, corn earworms and hornworms. Put up a bat box on a warm south wall, leave a night-scented corner unlit, and never spray after dark. Grow to recruit it: Evening Primrose,Honeysuckle,Nicotiana,Summer Jasmine
- Parasitic waspsBraconidae & Trichogramma Tiny, stingless wasps that lay eggs in or on caterpillars, aphids, and moth eggs — the white cocoons riding a hornworm are their calling card, so leave that caterpillar be. Umbel flowers with shallow nectar keep the adults fuelled. Grow to recruit it: Cilantro,Dill,Fennel,Lovage,Parsley,Sweet alyssum
See also
The Cottage Garden Companion — the gardener's bestiary at cottagegardencompanion.com