Check Your Oak Trees!

By Margo “Mac” McDowell, Fort Bend County Master Volunteer Coordinator

 

(Editor’s note: This article originally appeared last year in the Fort Bend County Cooperative Extension Horticulture Newsletter. Website references have been updated for this printing.)

 

Have you noticed anything different about your oak trees lately? Notice any leaves missing? If so, then look carefully, you’re bound to find a bunch of Yellownecked caterpillars (Datana ministra) chewing away at your leaves.

 

These caterpillars love to each leaves of our Oak trees! But they can also be found on cherry, crabapple, elm, maple, peaches, and walnut trees. They can grow to 2 inches long, and they have yellow strips along their orange to black body. What makes them stand out is that they have a “yellow neck” just behind their black head. They also have patches of fur. When you disturb them,

they immediately form a defensive mode by raising their head and their tips, like you see on the picture to the left. They are easily spotted not only because of their yellow markings, but because they are always in groups. They eat, and travel in “aggregates”. They are voracious eaters, and can strip a tree of its leaves in no time! Younger caterpillars will first “skeletonize” the leaf, but as it grows older, it will devour the leaves. Skeletonizing looks as though all the leaf has been eaten except the veins of the leaf which gives the appearance of having only the “skeletal” portion of the leaf visible.

 

One of the best ways to rid your tree of this pest is to pay attention to your tree and watch for signs of the caterpillar, such a branch or two becoming bare. If you see a small group of them, just cut that branch or tip off, put them in the garbage bag and toss them away. Defoliation is the goal of these caterpillars. Although it is unsightly for your beautiful tree to have no leaves, the health of the tree is not in danger.

 

For additional information, these websites are available:

 

http://insects.tamu.edu/fieldguide/cimg310.html

 

http://insects.tamu.edu/extension/bulletins/l-1835.html

 

http://hortipm.tamu.edu/pestprofiles/chewing/walnut/walnut.html

 

http://www.ppdl.org/dd/id/yellownecked_caterpillar.html

 

Yellownecked Caterpillar, Datana ministra (Drury)

(Lepidoptera: Notodontidae)

 

Photo by Dr. Bart Drees, Texas A & M University