I saw your last thread on the aphids, and I don't think they come in singles. IMHO I don't think you have aphids, but some weird, harmless summer-time bug. My last grow was outside, I saw green bugs like that on the stalk, but always in the shade. They never ate my girls or anything.
If you really want them gone though, there's some organic and not-so-organic stuff you can grab at just about any larger store. I saw some insecticide today at Wal-Mart for under 6 bucks. Came in a little spray bottle, said it was safe for veggies!