The winter has been very wet especially in February with only a few touches of frost. In the main, the bees have only taken defecating flights although there has been an increase of bees returning with pollen on their legs lately.
The mild, wet winter has meant that many plants are already shooting. The hellebores had been in full flower as have snowdrops and crocuses providing food for the bees.
In preparation for the coming spring, the floor has been placed in the hive. The edges and four sections have been marked with lines of petroleum jelly. The purpose of this is to indicate the level of varroa mites in the hive. The petroleum jelly gives some indication of where the infestation might be located. It also prevents any live mites from traversing the floor and getting back into the hive.
As a consequence of checking the floor varroa mites are present. Although only a few (8) it was decided to use oxalic acid to contain or reduce the number present in the hive. Whilst dripping oxalic solution onto the topbars is a common practice a decision was made to use the oxalic acid as a powder and heat it to form a vapor.
Great care should be used in the use of oxalic acid. As it is harmful to humans and in the vapor form can destroy lung tissue quickly, Therefore, disposable gloves should be used in the handling of the powder and a respiratory mask should be used; especially if heating it to create a vapor. The video below explains it in detail.
The main advantages of this approach are that the hive is not opened and that the vapor will permeate the hive and the resulting condense will be on the bees too.
A clean floor covered with petroleum jelly was added and will be examined in a week to see how many mites are present on the floor.
Ideally, this form of varroa treatment should be done around the end of December or early January. However, because of the long spell of wet weather, it was done later than normal.