Help Identifying Borers Killing Oak Trees
We live on 3.5 acres in Mt. Airy, MD. Our property is about 66% wooded, with wooded areas around two sides and farmer's fields on the other two. Over the past few years, we have noticed an increase in the death of our mature oak trees. Some of our trees I would estimate to be 75-100 years old. The trees seem to die and lose their bark. After cutting the trees up, the bark is rather easy to remove. And I have noticed these white larvae immediately below the bark layer. I assume that these borers are attacking the cambrium layer and killing the tree. Could you help me identify these insects? And could you recommend anything to help preserve the trees that remain and/or eradicate these insects?
The insect in your photo looks like a roundheaded borer, one of the long horned beetles. This is not the cause for decline. These borers come in after dieback.
In general, Trees can be affected by drought, poor drainage, planting too deeply, poor soils, soil compaction, etc. These factors make the trees susceptible to secondary issues like wood rots and borers. We have seen several years of stress in oak trees and decline.
At this point, all you can do is water the trees during dry periods. If you would like an onsite diagnosis, contact several certified arborists regarding the health of your trees http://www.treesaregood.org/