Each chomp leads to the next, forming a tunnel for their bodies to follow the mouth up front doing the chomping. Those tunnels appear as unsightly yellowish-white patterns on the green leaf surface. I have noticed that leafminers tend to avoid the outer edges of the leaf. The best means of control for leafminers is to pick the unsightly foliage and discard it in the garbage can for removal. However, over time, and with diligent observation I have worked out a more personally satisfying and rewarding method of leafminer extermination.
Equipment required is simple, cheap and effective on several levels.
The three tools required are one magnifying glass, a pair of fine tweezers, and one set of ear-plugs. You will need the magnifying glass, or a good loupe, to locate the maggot in its tunnel and to see the details of his mining equipment for tunneling. Once you have located and have a good view of the larvae you will be able to see the tiny miners lamp locate above the mouth. Take the tweezers and remove the miner's lamp. Without the lamp the leafminer is blind, but must continue feeding.