While the term "garden pest" may bring insects to mind for many people, it actually has a broader meaning that includes all insects and animals that interfere with the growth and health of plants. Diseases are considered to be a separate category from pests. There are five important categories of garden pests, but the particular garden pests that you may find will vary with your location.
Insects and other many-legged creatures: This group probably contains the largest number of different kinds of pests. Some are named for the crop they primarily damage, such as the Colorado potato beetle, the tomato hornworm, and the cabbage butterfly. Also prevalent, depending on where you live, are ants, aphids, borers, bugs, caterpillars and worms — such as gypsy moths and cutworms. centipedes, earwigs, grasshoppers, grubs and maggots, Japanese beetles, and weevils.
Mollusks: Snails and slugs, which resemble shell-less snails, are garden pests that chiefly attack members of the cabbage family and the lettuces.
Birds: Some birds, like purple martins, help control garden pests, but others are pests themselves. Crows and blue jays eat corn, and many birds may eat seeds and seedlings, as well as fruits, berries, and nuts. Species to be aware of include gulls, magpies, pigeons, robins, sparrows, and starlings. Geese and ducks, whether farm stock or wild, can also damage gardens.
Rodents and other small mammals: Small mammals can cause several types of problems, including eating plants and produce and digging in locales that you wish to protect. This group of garden pests can include armadillos, chipmunks, groundhogs or woodchucks, mice and rats, moles, opossums, prairie dogs, rabbits, raccoons, skunks, squirrels, and voles. Though not considered garden pests by most people, household pets, like cats and dogs, can be included in this category, depending on their behavior.
Larger mammals: Bear, deer, and moose are known to forage in gardens, and they are becoming more common in suburban areas. With the expansion of their territory, coyotes have also become a more common garden pest in places where they didn't used to roam. Particularly with bears, it is well to seek out expert advice on deterring and controlling behavior.
Pest control: There are a variety of means of controlling garden pests, depending both on the type of pest, and the particular approach one wishes to take. One can use deterrents, including companion planting, fencing, noisemakers, inflatable owls and snakes, and scarecrows. One can make the garden hospitable to pest-controlling creatures such as ladybugs, praying mantises, frogs, and toads. Other choices include homemade spray repellants (such as garlic spray), and commercial organic and inorganic pesticides. Traps in various sizes, including those that do no harm to the captured animal, are also available, sometimes on a borrowing basis. Advice about pests and how to protect your plants can be obtained from your state's Cooperative Extension Service (run through local colleges and universities) as well as local garden and farm supply outlets.