Tag Archives: Oxalic acid

Summer Oxalic Acid Varroa Treatment

Oxalic Acid

Oxalic acid is a very effective treatment for Varroa but only during broodless periods when the kill rate can be above 90%. When brood is present the kill rate is closer to 30% as most of the Varroa are in the brood where this acid cannot reach them. Click here for more on oxalic acid.

For this reason oxalic acid tends to be used during the mid-winter broodless period – if there is one!

However,  winter is not the only time bees are broodless and oxalic acid can also be used during summer broodless periods when the Varroa are phoretic (out and about on the bees).

Summer Treatment

Imagine a swarm…

Continue reading Summer Oxalic Acid Varroa Treatment

Mid-winter Varroa Treatment – December 2013

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Trickle treated 35 hives of bees with oxalic acid for Varroa today at 4 apiary sites. The temperature was 6 degrees, windy and beginning to rain. It took from 1.15pm to 4.15pm including travelling time so it has to be said it is the quicker of the two methods. If we had only the one Varrox Vaporiser it would have taken 10 minute per hive – which is nearly 6 hours and without the travelling time. Continue reading Mid-winter Varroa Treatment – December 2013

Winter Oxalic Acid Varroa Treatment

When the shortest day is upon us there is a brief broodless period in the honeybee colony. This is the time conditions are right for oxalic acid treatment. There are two reasons for this:

  1. When a colony is broodless, all the Varroa are at their most vulnerable out there in the open, either on the bees or creeping about on the comb – Varroa are protected from the effects of oxalic acid when they still inside the cells of the brood nest;
  2. Oxalic acid can damage open brood so these effects are minimal when there are no or few larvae.

On December 9th 2013 the bees were flying quite strongly and still working the last of the ivy and the Mahonia but there has been little activity since then. Any eggs laid during that spell of mild weather will have hatched by the end of December so that might be the best time to treat.

The following methods can be used during any broodless period, even in the middle of summer, but supers need to be removed. Click here for more about summer oxalic acid treatment. Continue reading Winter Oxalic Acid Varroa Treatment

Weather Warming Warning

The bees were very active over the weekend in the unseasonably mild weather. It is nice to see them so busy on the Mahonia and the late ivy, which is still in bloom here, but it is possible that it could scupper our hopes of a successful midwinter mite-cull. The bees will be bringing in nectar and little packets of fresh pollen which could get the queen laying. Should this occur then sealed midwinter brood would act as a refuge for Varroa and when we come along with our oxalic acid in a couple of weeks time they will be safely tucked away and the effects of the treatment will be minimal. Continue reading Weather Warming Warning