Found one in B&Q its called Provado ultimate bug killer.
Its about six pounds a bottle but is a concentrate and is systemic,
recommended for re-application after eight weeks.
I have given my lemon tree one application about four weeks ago and
thankfully no sign of scale or green bugs.
It recommends lightly spraying the plant until a fine mist is apparent on
the leaf surfaces without run-off ( A bit tricky) I just soaked the whole
foliage and bingo they have gone.

Regards. GKN
"dirt dibbler" wrote in message
ups.com...
Has anyone found a good cure for scale insects on indoor lemon trees?
I'm sick of trying to clean them off & having sticky sap & residue
everywhere.
A spray on would be good, but I'd try a systemic if thats the most
thorough way.

thanks
DD