Aphids do little damage to your plants when present in small numbers, however, they reproduce rapidly, so you should never ignore them. Aphids damage plants by piercing the leaves and sucking out sap. Any undigested sugars are excreted as honeydew; and quite often, sooty mold will appear on the honey-dew covered leaves. Aphids cause most of their damage from late spring to early summer outdoors; indoors, they are active all year. During a cool spring, they often multiply faster than their predators.

Aphids measure between 1/16 and ¼ inch long. Their soft bodies are pear-shaped and come in a wide range of colors. They have two short tubes projecting from their abdomens. They can be both winged and wingless. Their transparent wings are longer than their bodies. Nymphs are always wingless.

To control aphids, clean up your garden debris after harvesting to eliminate overwintering eggs. Till the soil in your garden beds deeply in the fall and again in the spring before planting. This practice will expose eggs to the elements and natural predators. Introduce beneficial insects into your garden; aphids have many natural predators, such as lacewings, lady bugs, and spiders.

To eliminate aphids from your garden, you can handpick them off foliage as soon as they appear in the spring. Prune infested shoots. You can also wash these pests off plants with a strong jet of water from a hose. To prevent aphids, mix 1 quart of water with 1 tablespoon dishwashing liquid, and 1 teaspoon vegetable oil. Shake well and spray on both the under and top sides of leaves. There are also plants that deter aphids that you can plant in your garden. These include chives, coriander, garlic, nasturtium, pennyroyal, petunia, southernwood, spearmint, and tansy. To protect your trees from aphids, spray them with dormant oil to kill aphid eggs.

For chemical control, Gulley Greenhouse carries Eight. To ward off aphid problems, keep ants under control. Ants "farm" aphids for their honeydew, protecting them from their natural predators.