Oxalic acid

[keswickb]

Did the second treatment of OA yesterday morning,did mite count this afternoon.Small hive had 12 mites, the strong hive had 176 mites in 30 hrs drop.Sure I keep up with OA or do some thing diffent? Like api var life.Need some feed back , new beek here. Thanks.

[rweakley]

That's sorta what you want to see. you had a ton of mites drop from the strong hive because the OA killed them. If I were you and was treating I would do 3 treatments about a week a part and then see what your mite drop looks like after that. I guess I am assuming you are doing oxalic acid vaporization, because you wouldn't do 2 treatments of the dribble method back to back it's much harder on the bees. By doing the 3 treatments with a week in between you should catch most of the mites outside of a capped cell during that 3 week period. I like OA vaporization as a crutch to get from bees that can't handle the mites to bees that can. I let mine go for multiple years unless I see signs of deformed wing virus then I hit them hard 3 weeks in a row. I DON"T lose hives to mites, I've starved a few, but not to mites.

[keswickb]

Yes using vaporizer,Hopes it gets all those little mites.Thanks

[RogerCrum]

I prefer to treat the at three weekly intervals in November when brood rearing has pretty much ceased so all of the mites meet their maker. However, if I were seeing signs of a heavy infestation, would not hesitate to do it now. All depends on whose ox is getting gored though. Best wishes.

[Mike Gillmore]

Those counts actually seem on the low side for a 30 hr period following an OA Vapor treatment in August. What were your 24 hour natural drop counts prior to treatment? If your vaporizer is working properly your colonies may be in better shape than you think.

[snl]

If OA is naturally occurring within the hive, can one use it while the supers are still on?

[rweakley]

I know it's naturally occurring in the hive, but I don't feel comfortable leaving supers on when I treat. If you have a ton of hives it might be a problem, but you can wait till the supers are off and hopefully you'd still have enough days warm enough (cluster break) to get 3 treatments in. I am VERY careful about what I do that could end up in the honey I eat and sell my customers. I have even taken supers off, treated and put the supers back on a day later (probably just stored them above another hive), this was for a hive showing too many mites.

[crofter]

Oxalic vapor only gets the mites on the bees and have read that it kills young brood. If you are going to do three weekly treatments there mite be a better option like hopguard (which supposedly is OK with honey supers on) It doesnt kill brood or disrupt laying which is critical in the coming weeks for us in the north, but maybe you have enough time yet that you can stand some brood interruption. Where Oxalic shines is after brood is all emerged and it is too cold for anything else to work, Yes it sure is cheap as well.

[Mike Gillmore]

I've never noticed any negative effects on open brood from Oxalic Acid Vapor applied correctly at three week intervals.

An additional single treatment on a warm day between Thanksgiving and Christmas, when the colony is broodless with a loose cluster, cleans them up nicely for spring build up.

[crofter]

Thanks, Mike;

I will throw that on the scale; Oxalic would be a quick, cheap and simple treatment. I was concerned about what I have seen written re. brood kill. Will be vaporizing in Nov. but doing some hopguard and formic at the moment with a few supers on; Will do a test extraction and see if I get any taste. Would like to have tested oxalic similarly but was chicken. It was 50 F. here this morning!

[snl]

Again since OA is natural in the hive, does anyone truly know if treating with OA with supers on is an issue?

[Andrew Dewey]

The OA level from applying OA vapors is unnaturally high. As OA has not been approved for use as a miticide in the US (not to my knowledge has anyone submitted an application to have it approved) I would be very leery of having elevated levels of OA in my honey. I do not have a scientific study to show that the OA levels will be elevated after vaporizing OA - it seems logical.

OA is often used (in countries where it is permitted) as a dribble in a sugar solution when the hive is broodless. As honey supers are not generally on then, there is less concern over contaminating honey. I would look to Canada as a source for scientific info on OA.

[snl]

From Scientific Beekeeping......for what it's worth....

Oxalic acid is extremely effective for the control of Varroa in brood free bee colonies. When applied properly, the three forms of application, spraying, trickling and vaporizing, have an efficacy of more than 95 %. A three-year study showed that the natural content of oxalic acid in spring honey is not increased. Thus, no residue problems are to be expected. The three treatments have shown a good bee tolerability and thus do not significantly differ in this respect from the untreated control.