It can be frustrating to spend hours in the garden, only to have pests interrupt your hard work. To a farmer, a pest is a destructive insect or animal that attacks crops. Gardeners would likely expand that definition to include ornamental plants. Both would agree, though, that it's important to know how to prevent pests in the garden, whether insect or animal. Here are some common pests and how to discourage them from making a home in your garden.

Common Insect Pests

Nature has no shortage of destructive forces, and insects are among the vanguard. They're part of a system of checks and balances in the natural world — but when they get out of hand, they can create disappointment for gardeners. Just ask anyone who's been deflated after seeing the skeletonized leaves of a linden tree from Japanese beetles or the sickly yellow mottling of tomato leaves from spider mites. Suddenly, they're desperate to know how to prevent pests in the garden. Identifying garden pests is the first step in dealing with the problem. Here are some of the most common insect pests you'll find in the garden, the telltale signs they're present and what you can do about them.

Aphids

Aphids suck juices out of plants, causing stunted growth and leaves that twist, curl and turn yellow. They also secrete a shiny, sticky waste product called honeydew, which attracts ants and can lead to unsightly sooty mold. Solutions include introducing ladybugs, also called lady beetles, which feast on aphids, or dousing plants with a stream of water to physically remove aphids. You can also spray plants with neem oil, insecticidal soap or pyrethrins, making sure to get the undersides of leaves, where aphids are often found.

Japanese Beetles

When you see lacy, skeletonized leaves, you can be sure beetlemania has arrived in full force. This invasion isn't anything to smile about, though. Traps, which attract beetles with pheromones, are a popular choice to try to get rid of Japanese beetles. However, unless you place the trap in your neighbor's yard, you'll just attract more beetles to your own garden. Instead, one solution is to go out in the early morning and at sunset and brush beetles off leaves and into a bucket of soapy water, which they can't escape from. You'll need to be vigilant, doing this once or twice a day for six to eight weeks. Additionally, contact spraying with neem oil or pyrethrins can help deter beetles, but follow-up applications will be needed.

Slugs

These slimy critters can take hostas from handsome to homely in no time when they get the munchies — which is just about any time they're slithering about. With large portions of their leaves eaten, hostas start to look ragged and forlorn. Treatment options include trapping slugs in tuna fish cans or other shallow vessels filled with beer (they're attracted to the yeast, fall in and drown) or hunting them at night with a flashlight and dowsing with a shaker of salt. You can protect individual plants by scattering crushed eggshells, sharp sand or diatomaceous earth around stems. Slugs won't crawl through the sharp material and should keep away from the plants.

Spider Mites

By themselves, spider mites look like tiny moving dots. But they're never on their own — they live in colonies, feeding on landscape plants including fruit trees, vines, vegetables and ornamental plants. Spider mites suck cell contents from leaves. At first, the damage is slight, with leaves showing a dimpling of light dots. Eventually, as feeding continues, leaves yellow and drop off. Telltale signs also include webbing covering leaves, twigs and fruit. A jet of water can dislodge them. You can also treat the affected plants with neem oil or insecticidal soap.