By your description here, I would suggest aphids, critters which were suggested on the other thread.

I posted additional info on your original thread which is here:
http://forums.gardenweb.com/forums/load/citrus/msg0109520123089.html?12

Here is a link that might be useful: your original thread

I had white flies ona grapefuit, leading to a bad case of sooty mold. Finally Neem Oil did it. Bugs are gone, and the sooty mold ais slowly getting taken care of, thanks to adice from others here.

Wow Jean...I think u are right. I had a friend that treats insects at agreen house nearby and she swear they are not. But would u belive that I have a little lime tree that I have not treated at all , all this time and just yesterday I noticed all these new growth leaves from it on the floor and said what the heck????LOL
So again as I do everyday. I took my magnafying glass and the plant to the light , and my GOD I saw aphids..I couldn't believe it. Adult ones and a few babies. I almost passed out. So I rinsed them off, found a couple of green lace larvea on one of the trees I am treating and put a couple on that spot, and watched them devour the rest of the aphids.....GOD speed to u for ur right guess. Thanks alot. I hope that these were the only critters I have on my trees, for I live in fear everyday of coming home and finding something else attacking them until the spring!!!LOL. As soon as see new baby growth I watch for bugs. I call it pestophobia of citrus! LOL
Growing citrus would be so much funner without the worry of pests, especially growing more than one tree since I have several of them I have to always worry about. It isd like having a tons of pets and once one has fleas, u worry about all the others..LOLOLOL. Thanks for listening and ur suggestions to all.