The use of powdered sugar dusting is a popular non-chemical approach to the control of varroa mite in honey bee colonies and is seen as an effective integrated pest management control (that is, one that does not rely on chemical intervention but good management practices.)
The method has proved to be an effective means of reducing varroa mites in honey bee colonies, having a significant impact on mite reproduction. When the bees are covered with powdered sugar their bodies become slippery causing the varroa to lose their ability to cling to the bees, the granules of sugar interfere with the gripping surfaces of the varroas’ feet and they fall to the floor of the hive.
The powdered sugar also causes the bees to groom themselves more frequently causing more mites to be dislodged. This technique does not appear to have any adverse effect on adult bees or brood. Unlike chemical methods this technique can be used at any time, even during a honey flow, as it does not contaminate the honey and as frequently as needed to control the mite. It can also be used as a method for detecting and assessing varroa mite infestation, within a colony.
How to apply powdered sugar to your honey bee colony
Take a sugar (or cocoa) shaker like the one pictured and use approximately 125 grams (1 cup) of sugar per single hive box. You should either have an open mesh floor or a sticky board in place, as the sugar does not kill the varroa but merely dislodges them. If not caught or dropped through a mesh floor the varroa will simply climb up into the frames again.
Smoke the colony as usual and put the sticky board in place on the hive floor if you are using one. Smoke the bees down from the top boxes. Remove the boxes and apply the sugar to the bottom box first, working up through the boxes. There is no need to remove the frames from the hive. Sift or dust the powdered sugar over the top bars of the frames and into the bees in the seams. Using a bee brush carefully brush the powdered sugar from the tops of the frames to between them.
The frequency with which you will need to apply this treatment will depend upon the level of varroa mite infestation.
The only down side to the use of powdered sugar for varroa control is if not used carefully it could potentially increase the chances of robbing by other bee colonies, during a nectar dearth and may also encourage ants. Even if you have an open mesh floor it is a good idea to apply a sticky board underneath to catch the sugar, this will also enable you to monitor the level of infestation in your hive.
Sticky boards can be purchased or made from cardboard or thick paper thinly smeared with a sticky substance such as vegetable oil or Vaseline.
