I apologize for this delayed reply to your gardening question and hope it is still helpful to you. I am not sure which larvae you may be seeing. Most cannot be controlled with exterior sprays once they are in the tree branch. I suggest using a soft wire in the holes to see if you can reach any larvae that way. Other than this old time technique you would probably need to use a general fruit spray for borers following label instructions on a fairly regular basis to break the life cycle of this pest. If the branch was dead when you found the larvae it could be that they are a secondary species that doesn't attack healthy trees but rather enter tree sections that are either dead or dying. Such pests do not need to be treated.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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