Hobbyist apple growers may dream of eating backyard apples only to discover that worms have overtaken the fruit. The culprit is typically codling moth – and those worms are actually pupating larvae, aka caterpillars.
The Codling moth is a common fruit insect, attacks a variety of fruit trees, including apple and pear trees. The female moths lay eggs directly on or near the fruit. Once the eggs hatch, the larvae chew into the fruit and work their way through to the core. When we talk about wormy apples, this is the insect that causes it.
There are two generations in a vast majority of cases, especially in drier climes such as Colorado. Therefore in our area, controlling this pest requires a two-step treatment.
We apply a spray to the foliage of the target trees until the leaves are wet. Timing is crucial for effective management – typically in May and again in July, although this can vary – our PHC team will customize the timing and treatment protocol to your situation.
What type of cultural controls work best to control codling moths?
For backyard plantings and small orchards, cultural controls are recommended as well.
- Banding, which involves wrapping the tree, can capture crawling larvae – but only for diligent and committed backyard gardeners. The band must be removed and burned or otherwise disposed of after the emergence, or it becomes more a promoter of codling moth activity than an inhibitor.
Apple and pear trees can be more susceptible to codling moth infestation if the trees are over-watered or over-fertilized.
Since apple trees are naturally drought-tolerant, they usually don’t require more water than falls naturally from the Colorado skies, except during severe drought years.
- Dedicated hobbyist growers might also consider bagging the individual fruit with a standard-issue brown paper bag.
- Also, selectively removing fruit that is touching will prevent the embedded larvae from having a path (or vector) to travel from one fruit to the next.
- Cleaning up fallen fruit is also recommended, as grounded fruit can become a mating ground which promotes the process of infesting/re-infesting the tree or neighbor trees.
Signs of codling moths may include pencil tip size boring holes, or a brown substance flowing out of the top of the fruit, known as frass, which is the excrement of the larvae.
What does the codling moth look like? The adult moth is grey with copper stripes on its wings and has an average wingspan of half an inch. The females lay eggs on fruit or leaves in summer and yellow larvae attack the fruit immediately upon hatching.
Codling moth and especially blight, another common fruit tree infection, are frequently controlled with a systemic insecticide which is injected into the trunk of the tree. This is done in areas where foliar spraying may be discouraged by neighbors, or with a tree located in a high traffic area that is vulnerable to over spraying.
A quick note about producing fruit trees in your backyard. If you’ve just bought a house that includes a producing apple or other fruit trees, it’s vital to verify the maintenance history of the tree.
The injectable treatment creates potentially poisonous apples which can cause short or even long-term damage when eaten. Make sure you verify this with the previous owner or HOA before eating.
Spring and early summer are when the first generations of moth adults emerge, so timing is critical.
Our plant health care experts will design a treatment plan that maximizes control and minimizes unnecessary or ill-timed treatment.