Answer: I would suggest you work with your local county extension to identify the beetles specifically and based on knowing that, decide whether or not treatment is needed. In some cases insect damage can be tolerated because it does not endanger the plant. If a chemical control is needed, they will have the most up to date information on what to use and how/when is best to apply it for maximum results.
If these are large trees, you may need to hire a professionally trained and certified arborist who has the proper spray equipment to treat them, so it is wise to obtain a specific identification of the pest and recommended control information first.
I hope it is nothing too serious.
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