Codling Moth
The larva of a small grey-brown moth (Cydia pomonella), 12 - 20 mm long and cream-coloured with a brown head. Adults emerge in late spring and lay eggs on developing fruit or leaves. Larvae tunnel directly to the core to feed on seeds, leaving a telltale entry hole plugged with brown frass. It is the most economically significant apple pest worldwide.
Symptoms to Look For
- Small entry holes on the fruit surface, surrounded by a small pile of brown-red frass
- Internal tunnels running directly to the core, packed with brown granular frass
- Fruit dropping prematurely in early - midsummer before it is ripe
- A small circular exit hole left in the skin when the mature larva exits to pupate
- Pink-cream caterpillar found inside damaged fruit near the core
Affected Plants
Organic Solutions
Kaolin Clay Spray
Mix wettable kaolin clay per label directions and apply from petal fall onwards, coating all fruit and foliage thoroughly. The fine particle film makes fruit surfaces unattractive for egg-laying and physically irritates larvae attempting to enter. Reapply every 7 - 10 days and after rain throughout the season.
Pheromone Traps for Monitoring
Hang one pheromone sticky trap per tree from petal fall. Traps capture male moths and let you time spray applications accurately. A trap catch of 5 or more moths per week is the action threshold for most organic programmes. Replace pheromone lures every 4 - 6 weeks.
Codling Moth Granulosis Virus (CpGV)
CpGV is a naturally occurring virus specific to codling moth larvae, approved for organic use. Apply as a spray every 7 - 10 days during egg hatch and larval entry periods (use pheromone traps to time this). Highly effective with regular applications; no impact on beneficial insects, birds, or mammals.
Corrugated Cardboard Bands
Wrap 15 cm wide bands of corrugated cardboard around the trunk in midsummer. Mature larvae leave fruit to pupate and will shelter in the flutes. Remove and destroy the bands every 2 - 3 weeks. In trials this can reduce populations by 30 - 50% when used consistently each season.
Remove Fallen Fruit Promptly
Collect and destroy all dropped fruit every 2 - 3 days throughout the season. Infested fruit contains maturing larvae that will go on to produce the next generation of adults. Do not add damaged fruit to a compost heap - bag it or submerge in water for at least a week first.
Prevention
- Hang pheromone monitoring traps from petal fall every season - accurate population data allows precisely timed interventions rather than routine calendar spraying
- Apply kaolin clay from petal fall as a season-long barrier - starting early before egg-laying begins is more effective than responding to first damage
- Encourage tits, woodpeckers, and nuthatches with nest boxes and winter feeding - these birds forage in apple bark and remove overwintering pupae at a significant rate
- Collect and destroy windfall fruit every 2 - 3 days throughout summer and autumn - this single step meaningfully reduces the next generation of adults
- Avoid storing damaged or suspect fruit near healthy fruit - larvae continue to develop in storage and will exit to pupate, producing more adults
Garden, by Willowbottom recommends only organic, wildlife-friendly solutions. No synthetic pesticides, no harmful chemicals - ever.