Aster leafhopper , Macrosteles quadrilineatus . They can be distinguished from other leafhoppers by the six dark lines on the face. The primary damage is from transmission of a plant pathogen that causes aster yellows in the lettuce crop. Leafhoppers may also damage head lettuce directly, although leaf lettuce is less sensitive. Row covers can be used to exclude leafhoppers from the crop.
Cutworms sometimes feed on young plants.
See Cutworm fact sheet. The leaves of lettuce and other garden plants may be eaten by slugs. These molluscs leave a slimy, iridescent trail wherever they crawl. They hide during the day and feed at night, notching the margins or cutting holes through the tender leaves. Slugs require a great deal of moisture, so eliminating moist, dark hiding places can reduce slug damage.