Keep your indoor plants pest-free with these safe and simple methods.

The most common houseplant pests are spider mites, scales, aphids, whiteflies, mealybugs, and thrips.  Look for the shiny, sticky deposits of honeydew these pests secrete on leaves and stems.  (You may notice black mold growing on the honeydew.)

Tiny spider mites produce fine webs.  Scale insects resemble fish scales on stems and leaves.  Aphids appear in clusters, usually on the undersides of new foliage.  Whiteflies are powdery white, and fly up in swarms when disturbed.  Female mealybugs deposit a white, cottony substance.  Almost microscopic thrips leave silvery scars on foliage.

Other warning signs include yellowing foliage, leaf drop, wilting, and listless growth.  To reduce damage, take action at once.

Isolate infested plants.  To make sure the problem doesn't spread, move infested plants to a separate, well-lit room and treat them using the methods below.  Keep them there for at least a month after treatment.  When you buy new plants, isolate them for a few weeks to make sure you aren't importing pests.

Try mechanical controls for small infestations.  Remove pests with cotton swabs dipped in alcohol.  Or place plants in a sink or shower, where you can blast away spider mites and whiteflies with a sharp stream of water.

Move up to insecticidal soap.  Available in most garden centers in ready-mixed aerosol or spritz bottles, insecticidal soap is most effective on soft-bodies pests such as aphids, young scales, mealybugs, spider mites and whiteflies.

Coat all surfaces of the plant, including the undersides of leaves, to thoroughly soak pests.  The soap works on contact and has no residual effect, so you might need to repeat the application in four to seven days.  To avoid leaf damage, hold aerosols 18 inches from the plant, and rinse off the soap after two hours.  Even though insecticidal soaps have low toxicity to humans, they can be mildly irritating to the skin and eyes, so use them with caution.

Horticultural insecticidal soaps are not the same as dish soap or laundry soap.  These soaps often damage plants, and they're generally not as effective in killing the insects.

Use "summer weight" horticultural oil for scales and more severe infestations. (Do not use heavier dormant oils.)  Made from highly refined petroleum oils, horticultural oils suffocate most houseplant pests.  They're available at nurseries and garden centers.

Whether using ready-mixedor concentrated insecticidal soaps or horticultural oils, carefully read and follow the directions.  When used as recommended, these products are safe and simple pest controls.

AN OUNCE OF PREVENTION.  The best way to prevent houseplant pests, especially during winter, is to grow healthy plants that can resist and recover from an infestation.

• Provide adequate light and moisture.  Most houseplants require at least 4 hours of sunlight or bright indirect light daily.  For brighter light, remove screens during winter.
• Don't overwater.  Give each plant a thorough drenching weekly, or when soil dries.
• Eliminate guesswork.  Inexpensive meters provide accurate light and soil-moisture readings for individual plants.
• Group plants together, use a humidifier, or grow houseplants on pebble trays filled with water.
• Avoid overfertilizing.  Pests thrive on overly lush growth.
• Keep cool. Most houseplants prefer temperatures between 60-75 degrees.  Protect plants from cold drafts, and place airflow diverters over nearby heating or air-conditioning vents.

GOOD LUCK AND HAPPY GROWING!