The aphids on the tropical have just exploded in the past week and the plant is covered with them. What can I use to kill them without harming the butterflies? Soap? Half-strength dormant oil spray?
Since the plant is in a pot, I suppose I /could/ hide it in into the garage for a day or two if I need to use something stronger like Sevin or Rotenone or pyrethrin. But I'd like to find a contact poison that leaves *no* residue.