Leafminers target foliage and young tender stems
Management options should be carefully considered since some treatments have the potential to be more damaging than the pests themselves.
By Noel Dickinson, BS in Agriculture, UH Hilo, 2014.
Vegetable Leafminer: Liriomyza sativae (Blanchard)

We’ve all seen them, white trails meandering across leaves in your garden. Most of us know leafminers are the culprits, but what is a leafminer? When these trails are observed they are usually empty, as if they’ve been traced by some phantom pest.
In mid-September, I observed what I believed to be leafminer damage on the foliage of hydroponic tomato plants in the hydroponic greenhouse, at the University of Hawaii at Hilo Farm Laboratory in Panaewa. I came to the immediate conclusion that the damage was done by leafminers because of the conspicuous grey, serpentine lines on the leaves of the plants, a symptom specific to all leafminer species.