Codling Moths on Apple Trees

Views: 4084

I’ve had three discussions in the past week concerning codling moths, starting with a gentleman at church who asked how he can keep the worms out of his apples.

I never thought a few worms in the apples were a big deal, but I recently found out the place where they burrowed and defecated can have toxins from mold growth. Yick. It’s a good thing to get rid of them.

Pheromone Traps for Codling Moths

Codling moths are a huge problem for apple growers, both backyard and commercial operations. They overwinter as the larval stage in silken cocoons, and will hide under the bark and it other nooks and crannies. Once the weather begins to warm, they’ll pupate and emerge as the moth right around the time the petals are falling from the trees.

One of the first things you should do, particularly in order to monitor the population, is to set up pheromone traps.

Pheromone traps are baited with the scent of a female moth, and if set higher up in the tree, can give you a good idea of what’s in the area. Check them weekly, and once you start seeing moths, or seeing the first “sting,” which is the little mark in the apple where they burrowed in to lay an egg, it’s time to treat the tree.

Kill Codling Moths with Sprays

There are a number of options, ranging from organic methods to the big guns of the chemical selection, but timing and consistency are important to make it effective. If it was me, the first thing I’d try is the codling moth granulosis virus (CMG-V). It’s a virus that affects the digestive system of the caterpillar killing it within a week. It’s organic, and scientists have proven it’s as effective as carbaryl when applied correctly. Spray the tree and the fruit thoroughly every week throughout the season. Adding a 1 percent of horticultural oil helps make it more effective.

Another biological product is spinosad, which is a naturally occurring bacteria that kills them. You need to spray it roughly 3 times during the initial hatch (10 days apart). You can spray it if there’s a second generation, although it’s recommended not to use it more than a half dozen times throughout the season. Plus, you need to have at least a week from your last spray to when you harvest.

Natural Solutions

Codling moths do have some effective natural predators. The Trichogramma wasp will use the moths eggs as a host for her eggs. As I mentioned in my last post, the folks at Woodleaf Farm in California have very few issues (practically none) with the codling moths since they forego tilling, creating a living mulch with ground covers, and ultimately a rich habitat for natural predators.

If you have a really bad infestation, it might be time to reach for the carbaryl (Sevin) to knock them. Use it judiciously since, remember, you are killing all of the beneficial bugs, including the valuable pollinators, as well as the codling moths. So you must never spray it during the bloom time, or the bees visiting the flowers are doomed (and they can potentially take residue of the spray back to the hive). In many areas the best time for the initial spraying is a month after petal fall (because it can cause the fruit to not set properly). And if you have to do it again, remember to not spray within at least a couple of weeks of harvest. (Read the label to make sure there are no changes to the restrictions.)

Prevent Codling Moths

Finally, keeping apples picked up off the ground, and removing any infected apples off of the tree will help you manage them. Also, check the apples you have in storage. If they have worm holes, they probably have worms, which can crawl out and overwinter in your storage area. You don’t want to provide a nice home for them so they can come back next spring and ruin your fruit.

The photo is copyright Zwilling330 from istock since I don’t have a good picture of a wormy apple (thank goodness!).

Meet Amy Grisak

Amy is a freelance author and photographer in Great Falls, MT who specializes in gardening, foods, and sustainable agriculture. She provides information on every kind…

Amy's Recent Posts

Leave hollow stems for native bees.
Hollow Stems for Native Bees: Leave the Garden a Little Messy
Read this post
It's important to know the allelopathic qualities of some garden plants, such as broccoli.
How to Know the Allelopathic Plants in Your Garden
Read this post

Amy's Videos

How to Safely Rid Your Indoor Plants of Pests
By Amy Grisak
Watch this video
Treating Fruit Trees for Fire Blight
Treating Fruit Trees for Fire Blight
By Amy Grisak
Watch this video

Membership Has Its Perks

Become a registered user and get access to exclusive benefits like...
  • Ask The Expert Questions
  • Newsletter Archive
  • PlantersPlace Magazine
  • Members Photo Gallery
  • Product Ratings & Reviews
  • Garden Club Samples

Here’s more information about gardening that you’re going to want