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gambel oak insect id and treatment #869695
Asked May 22, 2024, 9:13 PM EDT
We live on Cedar Mesa outside Cedaredge at 6400' elevation. We found rolled leaves, leaves with webbing and frass, and larvae from inside the rolled leaves. Hoping for your advice on diagnosis and treatment. Not widespread but we're concerned without management we could have a bigger problem. See attached photos.
Delta County Colorado
Expert Response
That could be from a kind of leafroller caterpillar. They feed on oak leaves and older larvae will fold over the leaf edge and secure it with silk. Generally, these cause cosmetic issues. In combination with other insects, they can contribute to extensive defoliation, but I'm not seeing evidence of feeding on the leaves in the photos.
Generally, leafrollers have many natural controls and don't require intervention. If you saw very high numbers this year, then, next year, you could apply horticultural oil on the twigs to target the overwintering eggs of this insect, but it is likely that no treatment will be necessary.
Here is some information for you: https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5347803.pdf
If you have further questions, you can bring in a sample to the Delta master gardeners. They are in the office 9-10am on Wednesdays, 525 Dodge St., Delta.
