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In this post I want to go over varroa treatment regimen. But before I do, I want to share another insight, this time from a local commercial beekeeper.
Similar to Zachary Lamas’ insight from the last post concerning drone population, mite load, and hive health, this insight pertains to worker brood population. It went like this: all spring and summer the bees have been raising a lot of brood. Because there is so much brood, the ratio of mites to 100 bees in a mite roll (he was doing an alcohol wash) stays well below the three mite threshold and hive health remains good. For a long time, it seems that everything is doing well.
Long about August, when brood production starts to taper off as nectar flow ceases and days start getting shorter (especially in our northern climates), that ratio changes dramatically and suddenly. Within a week or two the rolls will go from less than three to five, ten, or even twenty. This beekeeper’s conclusion is that, since there is less brood for mites to be in, they are now phoretic mites, riding around on adult bees and feeding on fat bodies that, being compromised, imperils individual adults as well as the colony health and longevity.
This all points, again, to the need to treat early—midseason. In the case of this commercial beekeeper, he will (next year. Beekeepers are farmers, they learn by experience.) probably treat when they pull the spring honey crop—around the end of June. This will knock the mite population back so that, when August comes, there is a greatly reduced population showing up in mite rolls and, of course, less mites to work their negative effects on a colony that is naturally lessening brood production and transitioning to a winter lifestyle.
Another accompanying reasonable conclusion: If you wait to treat till the mite count shows above 3 per 100 in a roll, it’s already later than is best. Which means we need to be treating prophylactically.
Ideally something like this (in southern Michigan. Make sensible adjustments for other areas of the nation.):
A formic product such as Formic Pro is particularly suitable since weather is cool. However oxalic vapor can be used in a 4 to 5 treatment regimen every 5-7 days can be successful.
Summer heat makes formic unadvisable unless you can catch a week of temperatures under 85 degrees. Oxalic vaporizing is probably the best choice but only if done in a 4 to 5 treatment regimen every 5-7 days. Another advantage in using oxalic over formic for this treatment is that the honey does not need to be removed.
Formic is a good choice if you can wait for cooler weather. If the colonies were treated in July, they may be able to wait untill the beginning of September for cooler weather. If the July treatment was missed, it would be good to do a regimen of oxalic vapor. If rolls are still showing higher than preferred mite counts, do a formic treatment in the beginning of September.
Preferably make this an oxalic vapor treatment and since they are broodless, one treatment is sufficient.
Missed the May and July treatments? Like much of life, start right now! And be extra diligent to make sure your treatment is effective by doing before and after mite rolls. Unlike early season treatments when there is some opportunity for flexibility, now time is of the essence and every day of delay translates into greater risk and likelihood of winter loss—exponentially.
In the above suggestions I have favored Formic and Oxalic. Other treatments can be used effectively, however, there seems to be more downsides.
If you haven’t treated for mites yet this season, you’re now fighting a fire—a three alarm fire. The sooner the better. Those mites are consuming that hive regardless what it might look like. And you, the keeper of the bees, are fighting for life. You no longer have time.
Don’t forget to feed heavily right now also! I’ll talk about that more next time.
