Some beekeepers often find themselves confused when it comes to scheduling the use of a gas oxalic acid evaporator when the brood is present. Other people suggest using three treatments that are 5 days apart, while some recommend three treatments at 7 days apart. Which is the best course of action, then?
It seems that the real question here is the length of time after a treatment that the oxalic acid will continue killing mites. As you might already know, a cloud of small crystals is sent into the air during oxalic acid vaporization.
These crystals quickly attach themselves to the hive and all its internal surfaces, including the woodenware, the combs, and yes, even the bees themselves. While this substance is not particularly dangerous to your honeybees, this can kill off varroa mites.
Several early reports stated that surfaces coated with the crystals were able to continue killing mites for a maximum of three weeks. However, if such claims were true, the mites would continuously get killed while emerging from the brood cells.
But ask any beekeeper and they will tell you that this is not the case at all. Some of the latest reports reveal that the oxalic acid levels in the hive go back to normal almost right away following the use of a gas oxalic acid evaporator, which seems to make more sense.
When trying to determine the amount of time you should leave in between treatments, it is important to know how long the chemical will remain active within the hive. It may be safe to assume that there is little to no residual effect at all.
Is It Safe to Use Gas Oxalic Acid Evaporator?
Before anything else, you might want to remember that some beekeepers are not really big fans of oxalic acid vaporization. Photos and stories of haze-filled apiaries with hacking, coughing, and half-blind beekeepers are shuddering. Of course, this may be a bit of an exaggeration but still, you get the point.
This means that once you have decided to vaporize, it is strongly recommended that you read and check the EPA label on how to use oxalic acid in beehives.