What is this?

[Saleh Abbas]

Does anybody know what is this in my tomato plant?  I'm afraid it is a disease, thanks

[christina soulia]

Looks like some kind of critter...reminds me of leaf miner tracks I see in spinach but never seen them on tomatoes. Good luck

[David - WI]

Yikes... that looks almost identical to the picture of tomato plant with leafminer on the Wikipedia page: http://en.wikipedia.org/wiki/Leaf_miner

[jamie niemeyer]

leaf miner :(

usually by the time you see this damage, it's already out n moved on to the next leaf..