I have followed with interest the work of Dr. Rodriguez using mineral oil to prevent varroa infestations. I am fortunate in not have to content with varroa in my hive management but there is one aspect that has not been raised to date which I believe is important. Does the mineral oil become a residue in the honey? Judging by the application method there must be a possibility that it will enter the honey at some time. I realise that it is food grade mineral oil that is used but, as mineral oil is not a natural occuring part of honey, then any that finds it way into honey must be classed as a residue. We now have greater standards for honey being required throughout the world. If something is not natural to a product then it can be present legally if a Maximum Residue Limit (MRL) is set for a particular item. This means that the particular item can be present up to the MRL. I think a lot of people would be surprised at what MRL's have been set for a range of food products. There could be an MRL for mineral oil determined for honey. I raise this issue now because I would not like to see a suitable method of control of varroa eventually denied official sanctioning because of a possible residue problem. Trevor Weatherhead AUSTRALIA