# Oxalic Acid Dribble



## Ian (Jan 16, 2003)

yes , the dribble apparently is very hard on the bees
one treatment per season max


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## Rusty Hills Farm (Mar 24, 2010)

I never use it more than once a season and then make sure I have little-to-no brood to get the best mite kill. I used to live in Florida and used it there too, again only once a season. Always had excellent mite kill with no damage to the queen or loss of brood. It has always been my understanding that multiple treatments will severely shorten the lifespan of your winter bees, which is why it is used once only.

HTH

Rusty


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## jim lyon (Feb 19, 2006)

A strong hive not be visibly set back by an oxalic dribble at all, I suppose you could reapply within a short time if there was a need but with a well timed dosage there really isn't a need. Mites will continue to fall for 4 to 5 days. A small hive (say 5 to 6 combs or less) will noticeably show signs of treatment, even though it is proportionally smaller. They will appear wet and stressed. I would retest after a week before making any decision on reapplying. Don't assume because a little may be good that more will be better.


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## Rusty Hills Farm (Mar 24, 2010)

From scientificbeekeeping.com:



> Heinz Kaemmerer of Heilyser Technology says:
> 
> “You can treat your colonies with a liquid mixture of OA and sugar but be careful. The liquid acid shortens the life of the bees. There is no problem during summer because the bee’s life not longer than approximately 6 weeks. The problem starts with winter bees–do not treat your winter bees more than one time with liquid OA. When using liquid OA bees get wet and have to clean each other. The result is, the acid ends up in their stomach and *during winter without a cleaning flight* it shortens the life of the bees. Two treatments on winter bees might kill the colony. Liquid OA is a slow killer and bees will probably die after a few weeks or month instead reaching the next season.”


and from that same article:



> As far as winter broodless dribbling, it is absolutely critical to treat them only once, with exactly the right amount and concentration of OA. More than one winter treatment clearly hurts the bees. Charriere and Imdorf (2002) found that colonies treated with 5-6 ml/seam of 3% OA were only 85% the strength of controls by April 25. The best review is in Anonymous (1999). Typically, winter bees treated with OA start out a little slower, but catch up by the end of March.


I thought I remembered reading this, so went hunting. Being from the Deep South with broodrearing going on almost continuously, this doesn't really impact my hives, but I can see how it might have a big impact on someone further north.

HTH

Rusty


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## Michael Bush (Aug 2, 2002)

The dribble damages their Malpighian tubules (equivalent of our kidneys). The general consensus (with some dissention) is that two treatments is too much...


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## acbz (Sep 8, 2009)

Here's a good study out of Univ. Nebraska where they experimented with a variety of OA treatments during both brood/broodless periods: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1000&context=entomologydiss

His conclusion was that it's not very effective during summer brood rearing but it didn't harm the bees, and highly effective during broodless periods. 

From Chapter 3 dealing with summer treatments: _"Repeated applications of OA did not significantly reduce the Varroa infestation on adult bees or in brood regardless of the concentration applied. The number of frames of adult bees, the square inches of capped worker brood, and the average weight-per-hive were not negatively affected by repeated applications of OA. My results do not support the use of OA as a summer treatment when colonies contain expanded brood nests. Although repeated treatments exhibited no harmful effects on bees, the paucity of significant mite population suppression indicates that repeated treatments are not useful in a Varroa management program."_

In my opinion, here in FL it's probably safe to do a couple winter OA treatments when brood rearing is at a minimum but still ongoing. I just finished doing an OA "cleanup" dribble on everything after 3 rounds of apiguard.


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## Michael Bush (Aug 2, 2002)

I think more than one treatment in summer when the bees are already short lived would be less of a noticeable negative effect than in the winter when you need long lived bees.


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## jim lyon (Feb 19, 2006)

acbz said:


> Here's a good study out of Univ. Nebraska where they experimented with a variety of OA treatments during both brood/broodless periods: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1000&context=entomologydiss
> 
> His conclusion was that it's not very effective during summer brood rearing but it didn't harm the bees, and highly effective during broodless periods.
> 
> From Chapter 3 dealing with summer treatments: _"Repeated applications of OA did not significantly reduce the Varroa infestation on adult bees or in brood regardless of the concentration applied. The number of frames of adult bees, the square inches of capped worker brood, and the average weight-per-hive were not negatively affected by repeated applications of OA. My results do not support the use of OA as a summer treatment when colonies contain expanded brood nests. Although repeated treatments exhibited no harmful effects on bees, the paucity of significant mite population suppression indicates that repeated treatments are not useful in a Varroa management program."_


I have experimented with summer treatments and this was pretty much exactly my impressions as well. If it hurt them it sure wasnt noticeable. My take was it might flatten the varroa expansion curve a bit.


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