Treating for Varroa without Chemicals
Monitoring mites should be started in spring, as soon as the bees start flying, through to autumn. Between those dates, weekly checks of mite drop should be carried out by removal, assessment and renewal of the sticky board. Different age colonies will have different average daily natural mite drop. For example a newly installed package will drop hardly any while a colony coming out of winter may have a steady drop. Establish what the average is and use that as a datum. The numbers will also vary according to colony size. The critical number is 50 mites dropped in any 24 hour period. This is considered the economic threshold and needs immediate intervention to save the colony. As you are monitoring the natural mite fall, any increase signifies a rising mite population and calls for spot sugar dusting treatment.
Directions for use of icing or 10x powdered sugar to control varroa mites:
(Caster sugar is not fine enough)
If the hives have a screened bottom board, a sticky board is set up underneath it allowing mite fall to be counted.
If the hives have a solid bottom board, a sticky card is laid onto the solid bottom board for the mites to be counted.
Items needed:
• Bee Brush.
• Measuring Cup.
• Cardboard or poster board to insert or slide under the hive to catch the mites to determine mite population. Place the insert into the hive before you use powdered sugar.
CAUTION: Do not try to hold the bar so the comb is horizontal TBH comb is not supported on all sides and will break off the bar!
To enable complete and adequate sugar coverage, either pull each comb and dust both sides or make enough space to dust one side then move the bar toward the rear and dust the other side. The sugar dust will have to be dusted gently but enough to turn all the bees white.
Determining The Mite Load
Use a sticky board. You can purchase one or even better make one by covering a thin board or stiff piece of card board with Vaseline or vegetable oil. Leave the card in place for 24 hours and then take it out and count the mites. When the count is 50 or greater you should sugar treat immediately. A more accurate count can be obtained by leaving the sticky board in place for 3 days and counting then divide by three and get a daily average. Again any average at 50 or over is considered to be the economic threshold or the point at which if left untreated would overwhelm the colony.
Treating
Fill you duster half way with powdered sugar and shake it, squeeze the container blowing the dust over the bees until they are totally white. Only a dust should come out and not big clumps. Do both sides of each comb with bees. Powdered sugar will not hurt brood.
Powdered sugar does not kill all the mites it interferes with their ability to grasp the bee and promotes a grooming behavior which knocks off more mites. To prevent them from climbing back up to parasitize more bees you will need the sticky paper in place. The dusting procedure will have to be repeated two weeks later to be effective enough.
Use this method in conjunction with regular monitoring of mite fall count and back it up with a drone culling method mentioned below.
Drone Comb Trapping
Freezing drone brood takes advantage of the mites' preference for drone brood. Put or find a bar in the hive that is primarily drone brood (Possibility of putting in drone foundation). Once the brood is capped, remove the bar and put it in the freezer. This kills the mites that are breeding in the drone cells. After freezing, allow it to thaw and put the bar back in the hive, the nurse bees will clean out the dead brood and mites. Continue the cycle of freezing/culling drones after the next drone capping.
Drone brood excision is another method. Cutting drone comb off when it’s capped reduces the mite load on the colony. It also allows for inspection and counting of varroa on the brood to determine the mite load on the colony.