Aphids
Aphids are small insects with soft bodies. They are shaped like teardrops, and the wingless varieties are most common in lettuce. They tend to feed in colonies and suck the sap from the lettuce leaves. They can transmit viral diseases to the lettuce and they also excrete a sweet, sticky substance known as honeydew, which produces mold and attracts ants. Some common aphids that attack lettuce plants include the potato aphid, the bean aphid and the turnip aphid.
Leafhopper
The leafhopper is a small, triangle-shaped insect that hops and flies. They may be brown or bright green and they are about 1/8 of an inch long. They pull sap from the underside of the lettuce leaf, which results in the leaf curling up and crinkling if the leafhoppers are not immediately treated. Use appropriate insecticides to deal with leafhoppers or lay sticky traps around the lettuce plants to trap the insects.
Worms
Loopers and army worms are two worms that cause severe damage to the lettuce crop. Loopers have a greenish color and they move by arching their middles up and then pushing themselves forward. Army worms may be green to black and they have more legs, allowing them to crawl over the lettuce leaves. Loopers leave behind greenish-brown feces that discolor the lettuce leaves and create holes in the plant, while army worms skeletonize the leaves. Use pheromone traps to contain these worms, or spray a pirethiod insecticide on your lettuce.
False Cinch Bugs
False cinch bugs tend to attack lettuce early in the season. They are about ? of an inch long, and they are a dull brown in color. They multiply rapidly, and they result in white discolorations on the leaves as well as shallow cavities in the leaf itself. Two substances that effectively control false cinch bugs are malathion and endosulfan.
As the above person said, specify which kind of flies. since there are numbers of flies in the universe.
When do flies eat lettuce? When it's growing/ ready to be harvested/ rotting?
