On Tue, 19 Nov 2019 09:29:16 +0000, wrote:

One of the many round tuits that eluded me earlier this year was to
spray woodworm killer on the joists and purlins in the sheds. A search
hasn't revealed anything authoritative about what time of year is best;
does the team think there is any point doing it during the winter?
(It needs doing because there was dust beneath some of the holes)

If you got holes they've been and gone. Does dust fall out of the
holes if you tap the timber? That means they only went fairly
recently.

I'd treat it, even it doesn't penetrate to any grubs in the timber
it'll get 'em as they emerge. It'll also get any new arrivals.

--
Cheers
Dave.