Native Plants

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Tuesday - November 26, 2013

From: Austin, TX
Region: Southwest
Topic: Trees
Title: Is a wasp colony in hollow in my oak tree harming it?
Answered by: Jimmy Mills

QUESTION:

I have wasps colonizing a hollow portion of a live oak here in my backyard in Austin ten feet from my backdoor. They are yellow and black banded, maybe an inch long. Two questions: 1. Are they hurting the tree? This live oak is very large, perhaps 700 years old, and the hollow is in a structurally critical part of the trunk. 2. If I have to kill them, what can I use that won't hurt the tree?? Help, please.

ANSWER:

Mr. Smarty Plants consulted a colleague who is an entomologist, and his guess is that you have yellow jackets (Vespula squamosa ). They are probably not harming the tree, but are using an existing cavity to build their nest. The colony was established by a single queen, and could contain as many as 4,000 workers. This link on wasp control urges caution when trying to eliminate a colony because of the high numbers of wasps involved. Colder months is a better time for eradication because the wasps are less active. The insecticides used for eradication probably won’t harm the tree.

This link from TAMU explains more about the yellow jackets, and bugguide.net has some interesting images.