Leaf Miners

This looks a case of leaf miner damage. These are tiny caterpillars of a small, brownish moth that tunnel into a leaf and eat it during their larval stage. They are usually easy to spot because they leave a trail or tunnel inside the leaf. But when there are too many, the damage forms a continuous look much like this. They are difficult to control, but here are some options:

Monitor plant leaves closely. At the first sign of tunneling, squeeze the leaf at the tunnel between two fingers to crush any larvae. Done soon enough, this killing larvae can allow plants to survive minor outbreaks. Pick off and destroy badly infested leaves in small gardens.

Use floating row covers to prevent fly stage from laying eggs on leaves.

Use yellow sticky traps to catch egg laying adults. Cover soil under infested plants with plastic mulches to prevent larvae from reaching the ground and pupating.

Organic neem oil will break the pestsäó» life-cycle by preventing larva from reaching maturity. Neem oil may also have repellent qualities and interfere with egg laying activities.