Jane McGary wrote "It is absolutely not true. Aphids have both winged and non-winged forms in the same species, and those with wings obviously get anywhere they want. I am told they can travel 300 meters or more especially if wind-aided." I'm sure that you have ants over there and these are one of the most important vectors for moving aphis around. The ants milk the aphis for their secretions so they like to put them on your juicy plants. So if you have lots of ants, get rid of them! Regards Hamish