.
Trickling seems to be allowed in UK
Animal and Plant Health Agency
Oxalic acid
At time of writing there is not a commercially prepared treatment
containing oxalic acid approved for use in the UK. Oxalic acid is
an ‘Annex II’ substance which
can be prescribed when
approved products are not effective or suitable and is applied by
trickling, spraying or sublimation. It removes phoretic mites for
up to about 48 hours, which means that it is very effective if no
or little brood is present but ineffective in the presence of
significant quantities of brood.
It is safest and most practical to obtain a proprietary, pre-mixed
and ready to use solution of oxalic acid from a bee supply
company. ‘OXUVAR®’ is available, which is approved for use in
at least one EU Country.
(Check the VMD website to check its
current status in the UK
http://www.vmd.defra.gov.uk/
public/bee.aspx) It is used in late November, December or
January when there is little or no brood. The crown board is
removed and 5 milliliters of the solution is dribbled on to each
seam of bees in the cluster using a calibrated syringe or drench
gun. It is only used once in the winter and is best carried out
with the outside temperature greater than 3°C. This treatment
cleanses the colony of the majority of the remaining Varroa
mites so that it will probably require no further controls until the
following August.
Conclusion
Oxaclic acid is allowed to use if there are no other choices. And other choices are not in temperatures near zero, and when it is brood brake in in winter.
As you may understand, you MUST buy a commerial product and you cannot do liquid youself.
But it is said, that commercial is safety and practinal.
It is not said that it is outlaw.