Frequency of oxalic treatment

[Phil Moss]

Oxalic will only kill phoretic mites, so how frequently do you have to treat to catch the next (and subsequent) batch of of mites emerging from the capped cells?

[fatshark]

I assume you're talking about vaporisation? You should not trickle more than once (though also see below).
5 day intervals, three or four times. Mite drop should be carefully monitored.
I think it was Pete Little who determined the interval empirically.

However, doing multiple vaporisation treatments contravenes VMD usage guidelines on the Api-Bioxal packet.
I believe BKA's are about to get a reminder of the importance of using only approved medicines as approved ...

[Phil Moss]

I assume you're talking about vaporisation? You should not trickle more than once (though also see below).
5 day intervals, three or four times. Mite drop should be carefully monitored.
I think it was Pete Little who determined the interval empirically.

However, doing multiple vaporisation treatments contravenes VMD usage guidelines on the Api-Bioxal packet.
I believe BKA's are about to get a reminder of the importance of using only approved medicines as approved ...

Interesting because I had come to the 5 day conclusion, having read that mites are phoretic for from 5 days up to 11, more at times, such as in winter. So if the interval is more than 5 days some will have entered capped cells and not be affected. But what effect does 3 treatments at 5 day intervals have on the bees?

[fatshark]

Other than make them hugely relieved to not have mites?

None.

Several studies have shown that vaporised OA is very well tolerated by bees - have a look at stuff from the Sussex Ratnieks group for example.

[Phil Moss]

Thanks, fatshark. I didn't notice any bad effects when I did 3 treatments at 7 days intervals last autumn.

[Watkins]

There was some anecdotal murmuring doing the rounds regarding brood mortality in open cells after each OA application.
Obviously less damage than the mites would have done but something to consider if the 3x5days regime needed extending in the event of continued high load.