Aphids: These small white, green, black, brown or orange pests are often found in clusters on tip growth and flower buds. A strong spray of water is usually enough to dislodge them—give an infested plant a good shower in your tub or outside with the hose.

Mealybugs: If you see tiny tufts of white cotton, usually clustered in sheltered areas of stems or on the underside of leaves, your plant has mealybugs. To control them, apply rubbing alcohol to individual mealybugs (the white tufts) using a cotton swab. Then wipe away with a damp cloth. Reinspect your plant and repeat this procedure every ten days until the pests are gone.

Mites: About the size of a grain of salt, mites are hard to see, but the damage they do is not. Look for mottled or stippled leaves, deformed flowers and very fine webbing over the damaged area. A strong spray of water will usually eliminate them—just be sure to spray both the tops and bottoms of leaves.

Scales: You won't spot scales easily as they blend in well against stems and leaves. The first clue of a scale outbreak is often sticky specks on a plant’s leaves or the tabletop. Check the leaves and stems directly above the sticky area for bumps that can be rubbed off. Rub off scales by hand. If they are stubborn, tap each scale with alcohol on a cotton swab to help it to release. If there are too many, find a chance to put the plant outside where the scales’ natural enemies can get rid of them for you.

Whiteflies: If you notice white specks flying up when you brush against a plant, whiteflies have set up camp. To control them safely, get insecticidal soap and spray it on the leaves, particularly on the underside (try the spray on a few leaves before spraying the whole plant to be sure it is not sensitive to the soap).

Cats: Some cats like to dig in potted plants; others use them for litter boxes. If your cats won't stay away from your houseplants, crush some rue leaves and spread them on top of the soil—the scent is very unpleasant to cats. Some cats can be deterred by sheets of aluminum foil near the plant.

Visit the following links for more information about plant disease and pest control:

Organic Gardening: Organic Houseplant Care

University of Minnesota: Houseplant Insect Control

North Dakota State University: Houseplant Care

Colorado State University: Managing Houseplant Pests