I have a problem with a mealy bug infestation on a newly bought
orchid, I have isolated it and have been treating by dabbing the
things with a q-tip soaked with methylated spirits. The trouble is the
things keep coming back after 2/3 weeks; is there anything systemic
(UK available) that is safe to use on orchids? Should I repot? (the
orchid is about to flower), Do they live in the soil?

Cheers

Dave.