As RoofTops says, a mite drop tray is not a reliable indicator of the degree of infestation by varroa. Be safe - not sorry is his advice and mine and, incidentally, FERAs. You have supers with capped and uncapped cells. Seems to me you should remove it all, take a reasonable proportion of it before applying Apiguard and hope that there is still time for the ambient temperature to be high enough (over 15 C) for it to be effective during the 4 weeks the treatement takes. Frankly you are in borderline country this late in the season. Some of the frames of honey, capped or uncapped, are worth retaining to be fed back after treatment. Hope this advice is useful. Oxalic at Xmas is the next step, coupled with some fondant as necessary. There again, if you don't Apiguard them, then trickling with Oxalic (which is a one-off treatment according to everything I can find on the subject) might not be enough to send your bees into the next season in good condition. For that reason, I evaporate oxalic as more than a single dose is quite acceptable. (On one of my hives I dosed then 4 times before the mite drop was OK - according to FERA's advisory leaflet on "Managing Varroa", available on-line but also available free from your Seasonal Inspector if you ask nicely). Maybe a beek in you local association has an evaporator and will dose yours for a small reward - mine's a single malt (afterwards of course)!!.