Question: When I harvest my broccoli heads I notice many small green plant lice on them. What can I do that won’t ruin the quality of the heads?

Answer: Those are aphids, also known as plant lice, as you indicated. You probably should be using an insecticide spray a week or 10 days prior to harvest, to keep them from becoming such a problem at the last minute. Rinsing the heads carefully prior to cooking will get rid of them.