100 grams Thymol crystals (handle with care - avoid skin contact)
200 grams PURA or other pure vegetable fat (no additives, preservatives or emulsifiers)
700 grams Castor Sugar
(sufficient for about 12 colonies)
Melt the PURA in a saucepan and allow it to cool until warm to the touch. Put the castor sugar into a plastic container and thoroughly mix in the Thymol crystals until all lumps are broken down. Add the sugar/Thymol mixture to the melted Pura and mix thoroughly until the mixture is the consistency of a paste.
If well sealed the mixture may be stored in the bottom of a refrigerator for up to 12 months.
On a piece of grease-proof paper about 10cm x 15cm spread the mixture so that it is about 5mm thick and place on top of the brood frames. The Crown board should allow a bee space above the paste. All ventilation should be closed except a 10cm wide entrance. Refresh the mixture very two weeks until the drop falls below 2-3 mites per week.
The ambient temperature needs to be above about 15C unless the hive is insulated. Expanded polystyrene works well (about 25mm thick) and can be left on all winter.
Note: do not apply the Thymol treatement when supers are still on. It is also advisable to remove excess winter stores in the spring before the bees transfer it into the supers.