pinch the tips out and spray with a soap solution to kill them.

thanks seaburngirl, [i like that name] have tried this , but, has not worked.

Spraying with soap solution needs to be fairly frequent, and very thorough. It will kill any of the blackfly it directly touches, but those you miss will repopulate the plant in as little as three days. Neem oil is almost the only organic remedy to have residual effect, but it is slow acting by itself.

Soap and water or the hose just as SBG says works for me

Thanks to SBG, Drc726, and Tugbrethi, have now tried this, I think my problem was, I didnot spray fairly frequent and thorough. So you live and learn from your mistakes, and, other peoples knowledge. Thanks for your advice..

Lol Carjam - 30 years ago I panicked because my potatoes plants had flowers on them.