OA

[swarm_trapper]

how late in the year can OA be used in the hive?

[Michael Bush]

Anytime the bees have broken cluster it works fine. If they are clustered the vapor won't penetrate the cluster very well. You could do it on a warm day when they are all flying anytime, but I try to do it when there are no supers and no brood.

[Axtmann]

Any time the year as long as the temperatures are a few degrees (3-5) above the frizzing point. No problem if they are in a cluster, the outside bees get covert with the acid fog and going inside the cluster to warm up. After a short time (day or two) the acid is in contact with all bees.
OA is the only effective treatment for the colder time of the year.

[wishthecuttlefish]

I am seriously considering trying Apistan strips on one of my hives. I have fogged three times with OA using the crack pipe method over the past 3 weekends, twice from the top and once from the bottom, and I am still getting about 40 mites dropping per day.

No signs of any deformed bees or wings, but I'm concerned that this hive might not make it through the winter if I don't get the mite levels down to < 10 per 24hrs. My other hive seems to be doing fine and has < 5 per 48 hrs.

So, whats the concensus out there? Should I try a couple more OA treatments and hope for the best, or drop in some Apistan? Where I live (MD) Apistan resistance has not been reported to be widespread yet.

Thanks,
Kai

[Axtmann]

Kai, Apistan works like OA it kills mites only outside the brood cells.

When treating with OA you can’t expect that all mites are dead the next day. After the treatment it takes at least 48 hours before mites starts die and falling down.

Apistan works over a period of 42 day and OA works similar but healthier to the environment and no resistant possible.

Go down to figure 2, 5 and 6 it shows how long OA works. http://www.mellifera.de/engl2.htm

Be patience, it takes a year or sometimes two to develop so many mites in a colony and you will get rid of it in 1 day.
Every beekeeper should take care of the bees during the whole year and not wait for the last minute.

Normaly beekeepers using OA to find out whether mites are resistant to Apistan or Checkmite but if you like to go the other way it’s up to you. Very soon there is no test necessary anymore, the chemical companies have no others in their backpack and the chemical using beekeepers will be stuck.

Herbert

[Axtmann]

Kai make sure your vaporizing the OA.

In a home made vaporizer it can be happen that the OA burns when using a torch and only the smoke from evaporation of the water comes into the hive and ash residue is left in the pipe.

Heat very slowly (3 mins) and give the acid time to evaporate. Evaporation temp of OA is approx 180ºC / 360ºF and with a torch you can reach 1000ºC / 1850ºF in a very short time.

[Michael Bush]

As long as brood keeps emerging that is infested you will keep having mites. It's not because the OA isn't working. I think this is a common misconception about a lot of treatments. Even if you kill every phoretic mite, you will still have mites in the brood.

[chemistbert]

Axtmann,
I disagree with you when you say that you will "burn" the OA I doubt that this is even possible as the thickness of the pipe used acts to temper the heat of the torch and since the OA is reasonably pure it should sublimate very quickly. I tried my pipe and all the OA was gone and a few seconds. But if you are using 2g and 75% of it sublimates the you are still getting a very nice sized dose.

I do agree with heat slowly anyhow but I don't think you would get too much decomposition even if you blast away with the torch. I think perhaps it is more iportant to heat evenly and not just in one spot. This avoids recrystalization in the pipe itself.

Just my thoughts.