I am not sure which "worm" that might be. If it is a caterpillar I doubt it is affecting the bark/trunk tissues in any way. If it is a beetle larvae (borer) it shouldn't be on the outside. I suggest you take a sample of the insects to your County Extension Office for identification, and if necessary, control recommendations. Their contact info is:
Texas Cooperative Extension
3033 Bear Creek Drive
Houston, Texas 77084
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