Definitely thrips, evil bastards, hate them more than you can imagine, love to munch tender seedlings and low leaves since they breed in the dirt and then the larvae climb up stems to the first leaves they find... EVIL EVIL EVIL!!!!!

Neem is good to protect older plants as you said but you might have to water your pots, ALL OF THEM, with predatory nematodes if you want to kill them organically.

Or you can just bug-bomb with pyrethrin once a week for 2 or 3 weeks and use yellow sticky traps to catch the stragglers.

Did I mention how much I hate thrips?
stinkyattic Reviewed by stinkyattic on . yellow wormy things won't go away! Ok so here's the deal- Harris7 and I have got these teeny yellow wormy things on our plants. They won't go away. They are so small you can barely see them, but they are eating our plants badly. We use insecticidal soap on all the plants whenever we spot one, and then we spray all the plants with a diluted neem oil mix every few days. I sprayed a bug with the soap once, waited an hour- and the wormy thing was still there, looking pretty dead to me (wasn't moving). It seems to me that the Rating: 5