We have a tropical milkweed that is frequently visited by Monarch butterflies. Wife picks the eggs off and raises the caterpillars in the house (safe from ants) and we feed them native milkweed (Asclepias syriaca.) She has released at least 100 butterflies so far this year. Anyway...
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.
Thanks, Bob