Question
QUESTION: I am in Georgia and have a crape myrtle that is about 2 years old.  We trimmed it back in Febuary.  This spring it has barely began to bud and we have noticed that there are these thread like growths that keep coming out of the tree leaving small holes when we brush them off.  It also is starting to grow a thin layer of moss.  I have used a insect spray now for 4 days but it hasn't stopped the growth of these threads.  Any suggestions as to what to do or what these threads are?

ANSWER: Sarah,

I don't know what this is but I doubt it is insect related. This sounds more like a fungus of some kind. What about these threads makes you think it is an insect? Could you possibly post a picture?


Jack DeAngelis, PhD
Extension Entomologist (ret.)
author Living with Bugs: http://www.livingwithbus.com/bug_book.html



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Crape Myrtle   QUESTION: It seems like an insect because it is like something is burrowing.  When you flake the thread off it leaves behind a hole in the tree.

Answer
Sarah,

Thanks for the picture. I'm pretty sure this is a wood boring beetle of some kind. I was thinking of a much finer "thread" in my original answer. The "thread" is actually sawdust that the beetle is kicking out of the hole. This material normally looks like ordinary sawdust, I've never seen it stick together like this.

These beetles bore through the bark and lay eggs in the wood. Larvae (beetle young) bore in the wood where they can do significant damage. The fact that moss is growing on the trunk may indicate that growth has already been impaired.

There are systemic insecticides that can be used against larvae but their success is somewhat spotty. One such "systemic" is Merit (imidaclorid), the product available to homeowners is called Bayer Advanced. Take a look at this page http://www.livingwithbugs.com/merit_insecticide.html for information about Merit (Bayer Advanced).

You can also treat the trunk with insecticide to prevent future attacks by the same beetle. Talk with a local plant nursery about a "trunk spray for wood borers" for use in your area.


Jack DeAngelis, PhD
Extension Entomologist (ret.)
author Living with Bugs: http://www.livingwithbus.com/bug_book.html