A healthy houseplant does more than simply look good. It improves the air quality of indoor living spaces, and can even act as mood lifters. If your plants are showing signs of poor health, inspect them carefully for signs of an insect infestation. Common houseplant bugs include thrips, whiteflies, aphids, mealybugs, spider mites and fungus gnats. Symptoms of a houseplant insect infestation include speckled or mottled leaves and visible eggs or insects. Use a hand-held magnifying glass when looking at the stems and leaf surfaces---some insects are difficult to see without assistance.
Isolate newcomers. When you obtain a new houseplant, isolate it for several days to be sure it hasn't brought any unwelcome guests into your home. Keep it in a separate room for at least a week.
Wash smooth-leaved plants with a mild detergent solution. Mix ½ tsp. of liquid dish detergent in 1 qt. of lukewarm water. Dip a soft cloth into the solution and swab the leaves and stems of your plants. Clean the underside of the leaves as well.
Set out non-toxic sticky traps to attract and kill whiteflies, fungus gnats, aphids and thrips. Hang the stiff, cardboard traps on branches or insert them into the soil. When the traps become covered with insects, remove and discard them.
Use non-toxic neem oil for whiteflies, thrips and aphids. Mix 2 tbsp. neem oil and 1 qt. of lukewarm water in a spray bottle. Add 1 tsp. dish soap and spray the plant from top to bottom, including the undersides of leaves. Spray the soil as well. Repeat weekly until no signs of insects remain.
Use insecticidal soap sprays on aphids, spider mites, thrips, scale mealybugs and whiteflies. Insecticidal soap is a safe alternative to toxic insecticides, but their killing power is short-lived. Reapply every four to six days. Spray the leaves, stems and soil for best results.
Use a pyrethrum spray for whiteflies, ants and aphids. It is available pre-mixed at lawn and garden-supply stores, and kills insects on contact. Spray the entire plant, including the soil. Keep plants out of direct sunlight until the spray has dried on the leaves.