Q: We have a question about how to control an insect that is destroying our otherwise healthy palo verde tree. Iβm enclosing a photo of the tree and three photos of what this insect is doing. In the latter you can see the little bored holes it uses to get inside a branch, what the branch looks like when it is done and the third shows some brown spots that may, or may not be related to the insect. Our friends think something similar might be destroying their mesquite trees, although they have never seen the attackers. Any thoughts?
A:Β Your tree is being attacked by the palo verde twig borer, a sporadic pest that seems to prefer pencil-sized branches to set up housekeeping. They hollow out the area near the holes in the branches, which become brittle and snap off on a windy day.
I see this damage around Tucson most years but not in very many places at once and not always in the same areas. There is not a good way to manage them because their occurrence is hard to predict and fortunately the damage isnβt long lasting or critical. I wouldnβt worry and I would try to think of it as natureβs way of pruning your palo verde.
Your neighbors might be referring to the mesquite twig girdler, which is also a beetle, but from a different family. Its MO is to girdle the twigs from the outside but the end result is similar, twigs fall off the tree. These are not a big deal either and another one of natureβs interesting ways of trimming trees.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to
