The best defense against damage to plants by insects is a healthy environment and early detection of infestation. Aerosol spray bombs are the handiest insecticides for indoor plants, but only those specially recommended for plants should be used and the directions followed exactly. The safest sprays contain pyrethrum or rotonone as the active ingredient. Systemic insecticides are applied to the soil and circulate through the plant, killing insects that chew or suck on it. This method eliminates the danger of inhaling spray mist where ventilation is poor and is very effective against white fly.
Lethargic green or black aphids that may appear on the tips of new shoots can often be removed by dipping the tips in soapy water. Another common indoor pest, the mealy bug, can be eliminated with a cotton swab soaked in alcohol. The more stubborn scale insects, if detected early, can be scrubbed off with a soapy brush. Spider mites are tiny, hard to detect, and difficult to control once established, even with special miticides. They resemble tiny dust particles and are usually detected under leaves that look crinkled or yellowish. If webs appear, the plant is badly infested. Since mites thrive in hot, dry environments, the best deterrents against them are high humidity and regular spray baths.