You have two problems. The "tracks" are leafminers, which are extremely prevalent this time of year on new growth flushes. The only "control" is a spray which contains spinosad. Some people spray nothing if trees are mature. Most home gardeners have very young trees and want some kind of control treatment. Spinosad-containing sprays are not cheap. Fertilome for caterpillars, borers, and leafminers is one brand that is available.
The second picture is cottony cushion scale which can be controlled with ladybugs or horticultural oil. HTH

Mike

Thanks for the information ... at least now I know what I'm battling!

I Googled the cottony cushion scale and found a page from UC Davis that indicated:

Natural enemies are the best method for controlling cottony cushion scale, so look carefully for their presence and avoid insecticides if you find evidence of them attacking cottony cushion scale. If natural enemies are absent, and the population is in a treatable stage, the organophosphates malathion or acephate (Orthene) can be effective.

I'm already have Orthene ... would that likely work as well as (or better than) the horticultural oil? ... (although I can't seem to find any "horticultural oil HTH" ... until it finally dawned on me what the HTH meant ... LOL)!

As for the leafminers ... which incidentally also seem to have visited the tangelo which grows about 10' from the Key lime ... I'll look for Fertilome. Also see two other spinosad products ... Monterey Garden Insect Spray and Bulls-Eye Bioinsecticide.

Thanks again for the identification!

If I were you, I'd be in my garden every morning and 'harvest" those scales by hand and flush them in the garbage disposal. I may treat my plant with alcohol on Q-tips too for assurance.