Obviously robbing bees and starving bees following the robbers can introduce a high load of Varroa into a hive but how common is this? and it is possible to get on top of a Varroa problem early if the time and effort is there.
Hi Tom
Try this: This appeared as an article in a recent issue of the Scottish Beekeeper magazine.
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Varroa – A Stitch in Time!
Eric McArthur
I thought of writing this event using a pseudonym, however I considered the odds and came to the conclusion that being virtually the only beekeeper in Scotland and - dare I say it Britain, fool enough to break ranks and strongly advocate publicly, over the years, the use of the organic acids to treat Varroa long before many could even spell oxalic dihydrate or who still have a pathological fear of formic acid, that a ‘cloak’ would be penetrated pdq.
In early January 2012, one of five colonies in a particular apiary in West Dunbartonshire, which similar to the other four colonies had indicated a negligible mite drop up to this point in time; quite suddenly produced a massive mite drop within a three day period. I would qualify this statement by stating that I (we) monitor the floor insert every three days, the year round, which proved to be a sensible time scale, especially if one is canny and does not follow the fashionable doctrine of renewing all the brood combs annually. The bees will produce a ‘heap’ ( I use the word literally!) of detritus inside that time scale when residing on ‘mature’ brood comb, making a mite count less than easy, if checking is done even on a weekly basis.
The late December weather had produced the odd flyable day and this colony (uniquely!) had obviously located a lucrative source of easy pickings in a ‘near distance’ colony, which also had masses of unwelcome guests. We immediately fumigated the colony with 1.5 g, oxalic dehydrate, using the short pipe in conjunction with a gas blowlamp. The following six days produced large numbers of mites on the insert and it became plain that many mites could have entered the ‘winter brood’. What to do? Formic acid is the only treatment which reaches the mites in the sealed cells – but formic acid requires at least 18 – 24 C to effectively evaporate it. No chance of such temperatures at this early stage. Hmmmmmmmmmm! Out of the question? I slept on the problem – and somewhere in the wee sma’ hours of the morning I woke with a ‘Eureka’ experience. Evaporate formic acid in the winter – a piece of cake!
We checked the other colonies floor inserts for mite drop over the next week – no worries!
The problem colony still had a high mite drop during this period (I work for a daily – ‘nil to negligible’ mite drop - the fewer the mites the lower the viral problems!) – so without ado we placed a 6”x6”x 3/16”, kitchen sponge on the brood frame top bars above the clustering bees, trickled 30 mls, 60% formic acid onto the sponge, placed a plastic sheet over the sponge and put a rubber hot water bottle filled with near boiling water from a large thermos flask on top and said a few ‘Hail Marys’. The mite drop was checked on schedule. Mite drop under control! A mite fall occurred over a period of fourteen days from the HWB treatment after which the drop ceased: The last of the treated sealed brood having now emerged with their dead(ly) cargo. The colony survived into the early summer - weakened but responded to a new queen from mid May. I requeen every year and all our colonies had new 2012 queens installed by late May.
All our colonies have been fed a 1 : 2 (sugar :water) syrup since early March – waiting on the hoped for weather window of 10 – 14 days unbroken sunshine with little wind. At time of writing the late summer nectar sources, lime, bramble, willow herb and privet have at best around 10 days of effective bloom left! Vive la Himalayan balsam – which will bloom effectively until the first frost.
Fairy tale, no! Maverick treatment – yes! Worth a try?? Even Nations need a ‘lender of last resort’ when all else fails – winter formic acid treatment could be your ‘Bank of England’ – one day – soon?