I am currently treating my loft timbers to protect them against woodworm. (There is woodworm already present). If I am effective at this is it possible and worthwhile to try to stop the beetles from entering the loft again via the eaves using a fine mesh screen?
Mesh screens won't do much against beetles as they will probably find other ways of entering and getting to the wood but I wouldn't worry if I were you. Wood-boring beetles prefer extremely damp conditions and sometimes even require already decaying, rotting wood, I doubt that this is your case. But if it is, you better replace all rotten elements with new wood with some sort of finish - beetles won't be able to penetrate the finish and won't be able to lay eggs. If you're worried because of observed exit holes but the wood is completely dry, you should know that this damage is probably a result of a previous infestation and this doesn't mean that the beetles will re-infest the wood. To be completely sure, though, you can apply a protective wood finish.
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