Nocturnal feeders come out in late evening or night, feed, and return to a hiding place as soon as the sun rises. Snails may travel several feet from a plant to hide in a dark, moist place during the day. Slugs also must return to a moist hiding place. If snails or slugs are involved, slime trails may give you a clue as to their presence. Earwigs, black vine weevils, and cutworms are all night feeders that retreat to hiding places in the soil during the day. To hunt for earwigs and cutworms, carefully scrape away the plant debris from around the base of the damaged plants. These insects may hide within a foot of the plant stem, and as much as a half inch deep in the soil. Earwigs will run away and hide as soon as disturbed, but if you see several in a short time of scraping and observation, they are probably contributing to the injury. Cutworms, if present, will be found in a little cavity, and will roll up into a spiral when disturbed. They are gray in color, and may be a half to one and a half inches long, depending on their stage of growth. Black vine weevils are gray-brown insects, usually about a half inch long (adults). They are hard to spot. However, if you have extensive weevil activity, you may find small, white grubs in the soil under and around damaged plants. The grubs feed on the roots, while the adults feed on the leaves and flowers.
Tobacco budworms may be present. This insect usually confines its feeding to buds and flowers. It is a day feeder and stays in the bud and flower portion of the plant throughout its development. However, once it is mature, the worm may pupate in the soil at the base of the plant. By the way, any pupa found in the soil at/near the base of the plant should be suspect.
Finally, birds and ants may at times be found feeding on buds, leaves, and/or young fruit. Harvester ants will cut up and carry away young seedlings and older plants. Some birds will also feed on flower buds and seeds or emerging seedlings. This is especially true during the migration periods of spring and late fall.
To control snails and slugs, clean up plant debris and eliminate hiding places. There are also numerous bait formulations available.
Use bird netting for bird control, and there are several ant baits that can be used for ant control, depending on the species of ant that is causing the problems.