This is best done early, before your lettuce becomes an irresistible hiding place. There are baits available for earwigs which are very effective although they may harm some beneficials. The damage shown at the left is not necessarily diagnostic of flea beetles. When disturbed they jump flea-like. Advanced damage results in a skeleton of veins.
Insecticidal soap can also be effective.
Be sure to test it on a small part of the plant to assure compatibility. Typically whitish or gray, dozens live in each gall. In Fall, as leaves begin to drop, eggs are laid on the bark of the host tree. The eggs hatch in early Spring and the aphids begin feeding on leaf stems producing honeydew, a sticky sugary substance that coats everything below the trees. Sometimes a black fungus will form on the honeydew.