I cannot improve much upon the FERA Varroa Management guides, which can be downloaded here:
They also have a useful Varroa calculator that I have used a few times.
My Varroa Management
Please read my Beekeeping Calendar for more information, but my interventions are:
- All Year – Open Mesh Floor
- April – Insert drone brood foundation. This is not described in the FERA guide but I have described it below and I found this technique described in the July 2014 BBKA journal written by The University of Georgia. I have found culling drone brood highly effective.
- Late July / August (after honey is removed) – Use Apiguard for 4 weeks
- December – Use Oxalic Acid (but only if it has been a cold winter and the hive is broodless – this requires 3 weeks at temperatures below 5C. I applied Oxalic Acid in December 2013 (mild winter) and it was not effective – so best not to use in these circumstances. Read: Applying Oxalic Acid)
Artificial and natural swarming will create periods of broodlessness and hence reduce varroa.
Using Drone Brood Foundation In April
- In April insert a frame with drone brood foundation into the brood box next to the outer frame of brood
- Remove when drone cells are capped (i.e. 17 days later if comb was already drawn)
- Place frame in freezer for 24 hours or until frozen solid
- Let frame thaw and then remove dead bees and larvae with uncapping fork
- Put frame back in hive for bees to clean up
- At this stage you can either (A) leave it in for another round of mite removal; or (B) replace with standard worker brood frame
- Protect/store the frames for the next 12 months so that wax moth don’t get them
Rationale For My Approach To Varroa Management
- Open Mesh Floor evidenced as effective way to reduce varroa plus easy, cheap
- Three interventions a year should suffice (drone removal, Apiguard, Oxalic Acid)
- Using drone foundation is cheaper and easier than using comb cage to trap queen
- I prefer the idea of using drone foundation rather than inserting a shorter brood frame so I can then replace that frame with a standard frame for the colony to use more effectively
- Apiguard reduces varroa population by 95% and is less aggressive than MAQs strips. I have started removing all honey by late July / start August in order for the bees to be able to build up honey stores for the winter and to be able to use Apiguard which needs temperatures above 15C.
- Oxalic Acid is effective under broodless conditions and reduces varroa population by 90%. It’s also relatively cheap. From now I only use during cold winters (described above)
- Apiguard is about £5 per treatment/hive; Oxalic acid is about £0.50 per treatment/hive
I have written a how-to on Oxalic Acid Treatment.
Here are some of my posts on varroa: