Orangestriped Oakworms: Defoliating Oak Trees

Orangestriped Oakworm

If you’ve started to notice your Oaks having bare branches and missing leaves, Orangestriped Oakworms could be the culprit. This native caterpillar feeds on the leaves of Oak trees, and sometimes other hardwoods, causing severe defoliation. This pest is usually noticed in late summer particularly August and September; however, heavy infestations can completely defoliate a tree by midsummer. 

Thankfully pests that defoliate trees later in the growing season don’t do as much lasting damage to the tree; however, it is still a cause of concern aesthetically and health-wise. The reason late-season defoliating pests don’t do as much damage is because the tree has already had a good amount of the season to collect and store energy from photosynthesis. Giving the tree enough energy to push out new leaf growth next year. Although any defoliation over 25% will begin to affect the vigor of the tree no matter what time of year. After repeated infestations, trees can also have trouble collecting the amount of energy they need and can become susceptible to other diseases and insects. On the aesthetic side, having a bare sickly looking tree in your yard during the summer and fall can be an eyesore. 

Susceptible Trees:

Orangestriped Oakworms feed on Oaks, hence the name. However, they do prefer Red oaks, scarlet oaks, pin oaks, and willow oaks over white oaks and chestnut oaks. Maple trees can also be susceptible, especially if they are near an oak that is heavily infested. 

Signs & Symptoms Of Orangestriped Oakworms:

  • Defoliation
  • Localized skeletonization of leaves
  • Adult moths around the trees (Females: yellow-orange with a silver-white spot and faint black line across the forewing. Males: smaller, and red brownish, but also have the white spot and pale lines)
  • Green caterpillars with yellow stripes on the tree(young larvae)
  • Black caterpillars with yellow-orange stripes up its side on the tree and on nearby sidewalks/pathways (adult larvae)
  • Yellow egg masses on the underside of leaves (typically seen in June or July)

Orangestriped Oakworm Treatment:

If caught early enough (typically in the egg-laying stage), the infestation can sometimes be pruned out of the tree. However, our Certified Arborists recommend treating infested trees and trees that have a history of infections with insecticides.

It’s also important to reduce other stressors on your trees such as soil compaction and drought in order to help your trees recover from Orangestriped Oakworm damage. Watering regularly as well as using aeration and fertilization can help your trees stay healthy and recover from defoliation caused by Orangestriped Oakworms. 

If you have signs of Orangestriped Oakworms on your trees we can help. Give us a call to set up an appointment with one of our Certified Arborists at 703-573-3029 or use our online booking system

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