Codling Moth in Nashi Pears | Nashipear.com.au

Codling moth (Cydia pomonella) is the No. 1 pest of pome fruit in Australia and the main reason backyard nashi crops get ruined. The larvae bore into developing fruit, leaving a brown tunnel and a small entry hole at the calyx end. Control is built on monitoring with pheromone traps, bagging or spraying fruit through the egg-laying window, and sanitation (picking up windfall fruit before larvae complete their cycle).

The same insect attacks apples and quinces. Anything you do for codling moth on a nashi works on an apple in the same yard.

What it looks like

Adult codling moths are small (about 10 mm long, 18 mm wingspan), grey-brown, with a coppery patch at the wingtip. They fly at dusk and are seldom seen during the day.

The damage is the easier identification. A small brown hole near the calyx (the dimple at the bottom of the fruit), often with a crumbly frass trail, and a brown tunnel running into the core when the fruit is cut open. A single larva ruins a single fruit.

Lifecycle in Australia

Codling moth overwinters as a mature larva inside a silken cocoon under bark, in cracks in tree trunks, in mulch, or in nearby sheds. Pupation happens in spring as soil temperatures rise.

Spring (Sep-Oct in southern Australia, earlier in subtropical zones): adults emerge, mate, and lay eggs on leaves and developing fruit. The “biofix” point used in the commercial degree-day model is the first sustained male catch in a pheromone trap.
Late spring to early summer: eggs hatch, larvae tunnel into fruit, feed for three to four weeks, then exit and pupate.
Summer: a second generation emerges, repeating the cycle. Warm regions (Goulburn Valley, Granite Belt, parts of Western Australia) often see a third partial generation.
Autumn: late-cycle larvae enter overwintering cocoons.

Apple and Pear Australia (apal.org.au) and Agriculture Victoria publish degree-day models that predict spray windows for commercial growers. The simplified backyard rule is to start monitoring at the first frost-free week of September and act as soon as trap catches climb.

Signs of damage in nashi

A small brown entry hole at the calyx end of the fruit, sometimes with crumbly frass at the surface.
A brown rotten tunnel through the flesh towards the core when the fruit is cut.
Premature fruit drop in December and January, with affected fruit often containing a fat pinkish-white larva.
Sticky residue and frass on the surface of stored fruit.

Russeted nashi like Hosui and Chojuro can hide entry holes in the russet texture, so inspect windfall fruit closely.

Monitoring with pheromone traps

A pheromone trap is the single most useful backyard tool. It uses a synthetic sex pheromone to attract male moths to a sticky base, which tells you when adults are flying.

Hang one trap per backyard nashi tree (or one trap per two to three trees in a small orchard) from late September in southern Australia. Hang in the upper third of the canopy on the south or east side, out of direct afternoon sun.
Check weekly. Count and remove caught moths.
Replace the pheromone lure every six to eight weeks per the manufacturer’s instructions (Yates, OCP, and other home-garden brands sell suitable lures).
The simple action threshold for backyards is to act when you start catching multiple moths a week.

Traps on their own do not control codling moth in a backyard. They monitor. The action steps below are the actual control.

Backyard controls

Bag the fruit

Fruit bags physically prevent female moths from laying eggs on the developing fruit. This is the most reliable organic answer for backyard growers.

Thin the crop first (one fruit per cluster).
When fruitlets are walnut-sized in November or early December, slip a paper or fine-mesh fruit bag over each fruit and secure the neck with a twist tie around the stem.
Leave the bags on until harvest.

It is fiddly on a full-size tree but transformative on an espalier or a small grafted nashi. Mesh bags are reusable; paper bags can be composted after harvest.

Pheromone lures and traps

In addition to monitoring, hanging extra pheromone traps (two or three per tree) can reduce male catches enough to mate-disrupt a small backyard population, particularly if your nearest neighbours are not running pears or apples.

Granulosis virus sprays

Codling moth granulosis virus (CpGV) is a naturally occurring virus that kills codling moth larvae as they chew into fruit. Commercial products include Madex and Carpovirusine. Home gardeners can use OCP Eco-Naturalure (a spinosad bait) or look for CpGV-based products at specialty horticultural suppliers.

Time the first spray at egg hatch, which the commercial model estimates as roughly 200 degree-days from biofix. The simplified backyard timing is one to two weeks after the first sustained male catches in the pheromone trap, then repeat every 7 to 10 days through the egg-laying window.

Cardboard bands on trunks

Wrap a 20 cm wide strip of corrugated cardboard around the trunk in midsummer. Mature larvae crawling down to pupate hide in the cardboard. Remove and burn or bin the bands every couple of weeks. This catches a meaningful percentage of larvae without using any spray.

Sanitation

Pick up windfall fruit daily through summer and autumn and dispose of it in the rubbish bin (not the compost). Each unmoved windfall fruit potentially adds a new moth to next year’s population. After harvest, clean up fallen leaves and old fruit mummies. In winter, scrape loose bark from the lower trunk where overwintering larvae hide.

Commercial Australian context

Commercial pear orchards in the Goulburn Valley and Tasmania run integrated pest management built on mating disruption (synthetic pheromone dispensers spread across the orchard to confuse males), targeted granulosis virus and insect growth regulator sprays, and intensive monitoring through Agriculture Victoria and Apple and Pear Australia networks.

Mating disruption is impractical in a single backyard but works well in groups of neighbouring orchards. Backyards near commercial pear orchards benefit from the area-wide control. Backyards in suburbs full of unsprayed apple and pear trees carry higher pest pressure and need stricter sanitation.

Note on fire blight

Codling moth is sometimes confused with fire blight (Erwinia amylovora) when both produce blackened shoots or distorted fruit. Fire blight is a bacterial disease, not an insect pest, and it is not currently established in mainland Australia. Any suspected sighting (sudden wilting and blackening of new shoots and flowers in spring, with a “shepherd’s crook” bend at the tip) is reportable to the Exotic Plant Pest Hotline on 1800 084 881. Do not prune or move suspect material.

Backyard checklist

Hang a pheromone trap from late September.
Thin fruit and bag what is left in November.
Apply granulosis virus or spinosad bait at first male catches and repeat every 7 to 10 days through summer.
Wrap cardboard bands around the trunk in midsummer and remove larvae weekly.
Pick up windfall fruit daily.
Clean up bark and debris in winter.

Do these and a backyard nashi will give you a clean crop most years.