Hope you get this! What you have are Asian leaf miners. They're new here. Supposedly they won't kill the tree, but I'm not convinced. You're supposed to treat with neem oil spray one week, and spinosad the next. My citrus are looking pretty bad, I need to get on top of this!

They are called leaf miners because they get inside of the leaves. Once they are in they are virutally impossible to get out.
External applications will not get inside of the leaves so to that extent you are wasting your time.
However, neem oil sprayed on the young tender leaves will stop the moth from landing on it in the first place. Don't over do-it. Reapply if rain washes it off and as the new leaves grow.
I have a young meyer lemon with the same issue. The neem seems to be stopping further infestations.
I doubt that it will kill the tree but it certainly seems to be able to stunt a limb.