Oxalic sublimation with brood in hive

[Magwat]

Just something puzzling me.
People frequently recommend on here 3 OA treatments 5 days apart when there is brood in the hive. That covers a total period of 10 days.
As the mites are going to be most plentiful in drone brood, which is sealed for 16 days I can't see how 3 treatments 5 days apart is going to catch all the emerging mites. Am I missing something very obvious.

 

[rook66]

Just something puzzling me.
People frequently recommend on here 3 OA treatments 5 days apart when there is brood in the hive. That covers a total period of 10 days.
As the mites are going to be most plentiful in drone brood, which is sealed for 16 days I can't see how 3 treatments 5 days apart is going to catch all the emerging mites. Am I missing something very obvious.

The first treatment should hit mites that emerged in the previous five days and are mature and ready to enter brood before sealing.Nothing written in stone with this, I have used it as an emergency treatment just to reduce the mite load.

 

[Little John]

I can't see how 3 treatments 5 days apart is going to catch all the emerging mites. Am I missing something very obvious.

I normally work with:
1x application when broodless, or 4x applications every 5 days when brood is present.
LJ

 

[MartinL]

Not 16
but not 10 either!
Every 5th day is 4 days apart!
Day 1, ... =1 day
wait 5 days =6 days
Day 7, ..... =7 days
wait 5 days =12days
Day 13, ..... =13days

 

[madasafish]

I had a hive last year with lots of brood and LOTS of varroa..
Four 5 daily OA sublimation and it was still terrible..(40+ drop per day).

A does of Apistan sorted it...(not used it ever before..)

 

[Magwat]

Thank you. I can see everyone's interpretation is different. I will make sure that I cover the full drone brood cycle.

 

[jenkinsbrynmair]

varroa mites have to stay on the bees for five days to harden before they can nip back into a brood cell

 

[Plenty of honey]

varroa mites have to stay on the bees for five days to harden before they can nip back into a brood cell

Thats really useful info JBM, thank you!

 

[SDM]

Vaping oxalic acid works at peak efficiency for about 72brs after treatment. So you gain a few days after the last treatment.

 

[jenkinsbrynmair]

People seem to think it's the 'vapour' that does the trick on the mites when in fact it's the desublimated tiny crystals that descend all over the hive and the bees afterwards - same mechanism as trickling really, the crystals stay in the hive for days and gets circulated around by the bees so even those that were outside foraging at the time of the vaping get a dose.

 

[jd101k2000]

Emyr, that's the first set of explanations that make any sense.

5 day hardening off and persistence of OA crystals.

When I looked at mathematical models of SINGLE treatments, rather than a sequence, a treatment to a brood-less colony gave protection for about 3 months, whereas a treatment to a colony with brood gave protection for only a week or two before the varroa would be back to the pre-treatment levels.

So, thanks for the information on how a sequence of treatments might be effective. That does make it sound as if a sequence of 4 treatments spaced at exactly 5 day intervals would be most effective. My only remaining quibble is that that does sound like a lot of work compared to other treatments.

 

[SDM]

. My only remaining quibble is that that does sound like a lot of work compared to other treatments.

Perhaps, but with so much less disturbance to the hive. No bearding, no brood breaks , no supercedures etc.