Several points occur to me
Why use it when you don't know if you have a problem?
It can do harm - you should know the potential problems
I have only seen it referred to as an autumn or winter treatment
I don't believe you should "bin" it. Read up on how to safely dispose of it.
Thanks for your concerns
1) my mentor who is a master bee keeper says to treat any swarm as prevention is better than cure. Allowing the mites into the brood will give them a good foothold and make them harder to treat once they have settled in. I have also read on here people advising to treat swarm with oa too.
Normally I would count the mites and then decide whether to treat, but as I am holiday there will prob be sealed brood when I return.
2) I do understand the risks. from here
http://scientificbeekeeping.com/oxalic-acid-questions-answers-and-more-questions-part-1-of-2-parts/
Does It Harm The Bees?
Ellis and Aliano found that OA is about 70 times as toxic to mites as it is to adult bees—which is a much greater spread than with either thymol or formic acid. The bees normally do not react defensively to being dribbled with syrup, but on rare occasions run out the entrance for a while. Occasionally one will notice a little adult bee kill after oxalic treatment. Adult bee kill does not seem to be an issue. However, there are questions about subtle effects, larval kill, and lasting suppression of brood development.
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.
3) your wrong. Again from same link
Spring/summer treatments
With summer dribbling, it is easy to overlook any effect of OA on brood rearing, especially if applied to late summer colonies that are not on a honeyflow, and were stressed by mites. Local anecdotal reports didn’t notice any frank effect, but they weren’t really measuring. One study of late gives us pause. Hatjina and Haristos (2005) is the only study I’ve found that reports significant problems to brood development following OA dribble. The authors recommend against summer treatment. The study was performed in Greece, “during the summer, between honey flows.” A question that is begging to be answered is: whether OA efficacy or brood mortality is affected by the amount of nectar flow during treatment.
Brødsgaard, et al. (1998) Treated colonies once in late March, and measured brood areas. “Neither the residues of oxalic acid in honey, the GST activity, nor the colony development after spring treatment with either trickling or spraying with oxalic acid seem to indicate any problems.”
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.”
Do not be in the “If a little’s good, a lot would be better” mentality with oxalic. It can be rough if over applied to the winter cluster, and is rough on the brood in the summer colony. However, be aware that most other treatments also affect the brood (amitraz, formic, thymol), queens (coumaphos), or drones (fluvalinate).
4) "Bin it" was an expression. Sorry if it came across as literal. It will be safely disposed of.
I still need an answer if possible to my question as I am flying soon.
Cheers
PC.
