There are a number of generalist caterpillars that can attack landscape plants, especially annual and herbaceous perennial plants. The following is more information.
A number of caterpillar species will feed on ornamental plants in the landscape. These include the well known pest such as bagworms, fall webworms, and eastern tent caterpillars. However, some pests more commonly associated with agricultural crops will also feed on ornamental plants. These include corn earworms, cutworms, various loopers, pansyworms, hornworms, and others. These are generalist caterpillars that readily feed on many plant species. Look for them on herbaceous perennials and annual bedding plants in particular. Caterpillar damage to bedding plants can be distinguished from slug or beetle damage because caterpillars generally consume large areas of leafs including all but the largest veins. Slugs will leave a messing trail of slime and feeding damage will appear irregular. Caterpillars in hanging baskets and small plantings can often be removed by hand. Commercial operators have a number of chemical options to choose from including the pyrethroid and spinosyn class insecticides.
Adapted from an article in the current North Carolina Pest News http://ipm.ncsu.edu/current_ipm/09PestNews/09News14/pestnews.pdf