They are definitely sucking. I can see their tiny proboscises stuck into the tomato skins and they are ruining the tomatoes they attack. Luckily, they seem to be herd bugs so all crowd onto the same tomato fruit together. So far, I haven't had to get out the big guns (Pyrethrum). After cutting one whole branch off, I am picking just a couple off every day or so. Actually not picking, shaking. They don't hang on very well. They seem to be attracted to the ripest fruits so I'm also picking a little early. I just can't figure out where they're coming from as I'm only seeing adults.