Slugs Snails Or Chewing Insects

Looks like snails or slugs but could also be caterpillars. Look under the leaves for caterpillars and remove them by hand if you find them (some of them are small and some of them can get quite large, like the Tomato Horn Worm). Look for snails and slugs at dawn or dusk and remove them and dispose of them. Also look for slime trails around the plants early in the day to indicate their presence. If you have an area of your garden or landscape that may be harboring snails, we recommend trapping them and/or collecting them from the area every morning until you’ve eliminated them (or as much as possible). Snail baits must be used exactly right to be effective and can be toxic to children and animals. Since snails/slugs lay eggs in soil, we also recommend regular cultivation of the soil with a hoe or claw-type tool around the yard/garden, but avoid damaging plant roots. This link provides great info about managing snail/slugs.
http://www.ipm.ucdavis.edu/QT/snailsslugscard.html