Orange and Black Striped Oak Caterpillars - Ask Extension
3-4 years ago a Willow Oak (10 " diameter) in our yard was infested in late summer with Orange and Black Striped Oak Caterpillars. They were identifie...
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Orange and Black Striped Oak Caterpillars #443109
Asked March 11, 2018, 9:21 AM EDT
3-4 years ago a Willow Oak (10 " diameter) in our yard was infested in late summer with Orange and Black Striped Oak Caterpillars. They were identified through Cooperative Extension, a picture is attached. I had never seen them before this and have resided here for 25+ years.
Am I correct that the general advice is that they do not cause lasting damage and do not require treatment? They have defoliated about 40-50% of the leaves of the Willow Oak annually since they arrived, and for the last 2 summers have done the same thing to a Pin Oak (15" diameter) about 100 yards away at the opposite end of our lot. The Pin Oak has lost some of the lower branches, though I am not certain that this caterpillar is the cause.
Is there any environmentally safe prevention we could use such as a dormant oil spray? 50 feet from the Pin Oak there is a 5' Wye Oak Sapling planted 4 years ago. Any suggestions on protecting it from infestation? Is it more at risk for damage or loss because of size/ age?
Thank you
John
Frederick County Maryland
Expert Response
John,
Generally the control of orangestriped oakworms is usually not warranted, except to control caterpillar nuisance and to protect weakened or high value trees. If you want to control them, you can apply a pesticide with Bacillus thuringiensis (Bt) when the caterpillars are small. This is a natural bacterium that kills caterpillars. Pin oaks need regular watering to do well. The loss of lower branches on your pin oak might be due to drought or a combination of drought stress and the caterpillar feeding. Keep your Wye oak sapling well watered too, as it is still relatively young. Trees that are stressed by drought are more susceptible to insect and disease problems.
I hope this helps. Let us know if you have additional questions.
ckc
Generally the control of orangestriped oakworms is usually not warranted, except to control caterpillar nuisance and to protect weakened or high value trees. If you want to control them, you can apply a pesticide with Bacillus thuringiensis (Bt) when the caterpillars are small. This is a natural bacterium that kills caterpillars. Pin oaks need regular watering to do well. The loss of lower branches on your pin oak might be due to drought or a combination of drought stress and the caterpillar feeding. Keep your Wye oak sapling well watered too, as it is still relatively young. Trees that are stressed by drought are more susceptible to insect and disease problems.
I hope this helps. Let us know if you have additional questions.
ckc
Thank you for your help!
You're welcome!
