Codling moth damage on developing apples.
We recently spoke with agronomist Chris Hammond, who has spent much of his career advising fruit growers and later managed apple orchards in Washington State. We asked him what the biggest insect challenges are that growers face in their orchards.
Codling moth was the first one he named.
“They burrow directly into the fruit and they are hard to control.”
How Does the Worm Get Into the Apple?
Codling moths lay their eggs on leaves or developing apples. After an egg hatches, the tiny larva crawls to the fruit and begins chewing its way through the skin. Brown, crumbly material called frass can collect around the entry hole. Chris showed us an example on an apple and gave us the less technical definition: it’s the worm’s poop.
From there, the larva works its way farther into the apple and feeds inside the fruit. Cut open an infested apple and you may find exactly what Chris described:
“If you see a little pink guy in there, that’s your codling moth.”
What growers are trying to catch is the short period after the eggs hatch and before the larvae burrow into the fruit. Once inside, the apple becomes a shield.
A spray applied after that point is what growers call a “revenge spray.”
“You’re killing the bug,” Chris explained, “but you’re not really accomplishing anything.”
That window shifts with the weather. Codling moth develops faster in warm weather and more slowly when temperatures are cool, so the right treatment date can change from one year to the next. Chris recommends using university pest-timing information for your area rather than relying on a fixed calendar date.
Start by searching codling moth + your state + Extension. If your state doesn’t publish clear guidance, a search engine or AI tool can help you find the best university information for your location. You can use this prompt:
I have a home apple tree in [city, state]. Find current university or Cooperative Extension guidance for codling moth in my area. I want to know when treatment is typically recommended and how local weather may shift that timing. Look for current home-orchard spray schedules, pest alerts, or codling moth timing information, and prioritize university or Extension sources.
How Can You Tell When Codling Moth Is Active?
One way to get a better idea of what is happening in your own tree is with a codling moth delta trap. The trap uses a pheromone lure to attract male moths to a sticky insert. Chris recommends hanging it high in the tree and checking it regularly.
A single moth in the trap doesn’t necessarily tell you when to treat. What matters more is seeing continued activity over consecutive checks. That can help establish what growers call a biofix—the beginning of sustained moth activity in your area.
From there, you can use that date with a local university codling moth model or Extension guidance to better estimate when eggs are likely to hatch and when treatment would be most useful.
What Can You Actually Use?
Once codling moth eggs begin hatching, there are several ways to protect the fruit—and they don’t all work the same way. Some treatments kill the young larvae directly. One uses a naturally occurring virus that infects codling moth larvae after they eat it. Another doesn’t poison the insect at all; it covers the apples and leaves with a fine layer of clay that makes the tree a less inviting place for moths to lay their eggs.
That gives a home grower four main treatment approaches:
Note: The homeowner product examples below come from our own follow-up research and are not product endorsements from Chris.
| Approach | What it actually is | Product examples | Advantages | Tradeoffs |
|---|---|---|---|---|
Conventional insecticide |
A synthetic insecticide that kills codling moths or exposed larvae before they enter the fruit. |
Product examples:
GardenTech Sevin Insect Killer Concentrate
Bonide Fruit Tree & Plant Guard
|
|
|
Spinosad |
An insecticide made from compounds produced by a naturally occurring soil bacterium. Young larvae are killed after exposure. |
Product examples:
Monterey Garden Insect Spray
Captain Jack’s DeadBug Brew
|
|
|
Codling moth virus |
A virus specifically used against codling moth. Larvae eat the virus while crawling or feeding on a treated surface, and the infection kills them. |
Product examples:
CYD-X HP
Madex products
|
|
|
Kaolin clay |
A fine clay mixed with water and sprayed onto the tree. Once dry, it leaves a pale coating that makes the tree a less inviting place for moths to lay their eggs. |
Product example:
Surround WP
|
|
|
What Can You Actually Use?
Once codling moth eggs begin hatching, there are several ways to protect the fruit—and they don’t all work the same way. Some treatments kill the young larvae directly. One uses a naturally occurring virus that infects codling moth larvae after they eat it. Another doesn’t poison the insect at all; it covers the apples and leaves with a fine layer of clay that makes the tree a less inviting place for moths to lay their eggs.
That gives a home grower four main treatment approaches:
Note: The homeowner product examples below come from our own follow-up research and are not product endorsements from Chris.
CONVENTIONAL INSECTICIDE
What it is: A synthetic insecticide that kills codling moths or exposed larvae before they make it into the fruit.
Product examples: GardenTech Sevin Insect Killer Concentrate; Bonide Fruit Tree & Plant Guard
Advantages: Generally more forgiving than some of the softer options because the product can remain active on the tree for a period of time.
Tradeoffs: These products can also affect beneficial insects, including bees, so label directions, bloom restrictions, and preharvest intervals matter.
SPINOSAD
What it is: An insecticide made from compounds produced by a naturally occurring soil bacterium. Young codling moth larvae are killed after being exposed to it, so it still has to be on the tree at the right time.
Product examples: Monterey Garden Insect Spray; Captain Jack’s DeadBug Brew
Advantages: Available in homeowner-size products, and these examples are approved for organic gardening.
Tradeoffs: It doesn’t give you unlimited protection. Good timing and repeat applications may be needed, especially where codling moth pressure is high.
CODLING MOTH VIRUS
What it is: This one really is a virus—but one used specifically against codling moth. The larva eats the virus while crawling and feeding on a treated surface. The virus infects the larva and kills it.
Product examples: CYD-X HP; Madex products
Advantages: Extremely targeted. Rather than spraying a broad-spectrum insecticide over the tree, you are using something aimed specifically at codling moth larvae.
Tradeoffs: The larva has to eat it before disappearing into the apple. Coverage and timing are important, and these are more specialized products that may be harder for a homeowner to find.
KAOLIN CLAY
What it is: A very fine clay mixed with water and sprayed over the tree. When it dries, the apples and leaves are left with a pale clay coating that discourages moths from laying eggs on them.
Product example: Surround WP
Advantages: No conventional insecticide is involved, and the clay works as a physical deterrent rather than poisoning the moth.
Tradeoffs: The tree really does look coated in white clay, and good coverage has to be maintained. For codling moth, kaolin is generally used as a suppressive tool rather than something to rely on for complete control.
Whatever product you choose, read the current label for apples, codling moth, repeat intervals, and preharvest timing.
Chris’s experience with organic orchards was that these approaches can work, but some leave less room for error. If a treatment doesn’t last as long, or the larva has to eat it before entering the apple, missing the right window matters more.
What If You Don’t Want to Spray?
Thinning
If you’d rather avoid insecticides, there are still practical ways to reduce codling moth damage. The first is thinning—removing some of the young apples so the remaining fruit has more space to grow.
For apples, university guidance generally recommends leaving one good apple per fruiting cluster, choosing the largest, healthiest fruit and removing the smaller or damaged ones around it. On heavily loaded branches, the remaining apples should also have some space between them rather than growing in tight bunches. Thinning improves fruit size and quality, reduces the load on the tree, and makes it much easier to protect and inspect the apples that remain.
Fruit-Protection Bags
Once the clusters are thinned, the remaining apples can be protected individually with fruit-protection bags.
Fruit-protection bags are small bags made to cover individual apples as they grow, creating a barrier between the fruit and insects. They are roughly the size of a small lunch bag, with enough room for one apple to grow inside. Standard paper lunch bags can work, and purpose-made apple bags are also available. Because some styles are more effective against codling moth than others, a recommended example and purchase link are included in the Additional Resources section at the end of this article.
The bags are added while the apples are still small—about ½ to 1 inch across—and before codling moth damage appears. The opening is secured around the stem without pinching it, while the bag remains loose enough for the apple to continue growing inside.
Roguing
Even with thinning and bagging, Chris recommends checking the tree at least once a week for apples that show codling moth damage. Removing those apples before the larvae leave the fruit can help interrupt the next generation of moths.
Removing damaged fruit this way is called roguing.
Chris explained:
“If you throw it on the ground, eventually that worm will come out and pupate and come back next year. So when you rogue them, you've got to throw them somewhere far enough away, which if you don't want to throw them in the garbage, chop them up or smash them or take them an hour away, disintegrate them so that insect dies.”
What’s Growing Around You?
A nearby apple tree can make codling moth much harder to manage. This is called insect pressure—the amount of codling moth activity around your property. A neglected tree with damage on nearly every apple can create a lot of pressure.
Distance helps because codling moths tend to stay where food is available. As Chris put it:
“If there’s a couple apples here and here, most codling moths don’t want to leave their area. That’s home.”
But a large population can still matter from farther away. Chris gave the example of a dozen heavily infested trees half a mile away: some of those moths are still going to find their way toward you.
Getting It Just Right
After talking through codling moth and the work it can take to stay ahead of it, we asked Chris what he still enjoys about growing fruit after 25 years in agriculture.
“I just like going out and seeing things grow. Unfortunately, everything out there when you’re commercially doing it seems to want to inhibit that perfect growing fruit. So whether it’s bugs or something like iron deficiency, I would see it and be like, ‘Oh, it’s not just right.’”
That is also part of what keeps him interested—the chance to figure out what is happening and find a better way to deal with it.
“The more you know, the more you can pick up on all the little flaws and you’re just like, ‘Oh, I want that to be just right.’ I just want it to be perfect. It’s not too much to ask.”
Additional Resources
Fruit-Protection Bags — Example Product
One example of a purpose-made bag for protecting individual apples as they grow. This is just one option; other suitable fruit-protection bags are available.
View the fruit-protection bags on Amazon →
Colorado State University Extension — Codling Moth: Control in Home Plantings
A detailed homeowner guide covering codling moth identification, thinning, removing infested fruit, bagging, and treatment options.
Read the Colorado State University guide →
UC Integrated Pest Management — Codling Moth
A useful reference for identifying codling moth damage, understanding its life cycle, and reviewing nonchemical and treatment-based management options.
Read the UC Codling Moth guide →
Find Your Local Cooperative Extension
Codling moth timing varies by climate and location. Use this nationwide directory to find university Extension information for your state, including locally appropriate pest timing and treatment guidance.
Find Cooperative Extension in your state →
Codling Moth Interview with Chris Hammond
Watch our conversation with agronomist Chris Hammond as he shares what he has learned from 25 years in agriculture about codling moth, why treatment timing matters, spray and no-spray options, and managing insect pressure around apple trees.
