Identification is the first step in house plant insect control. Once you have determined the problem, you can determine what method of control to use. Insecticides will be necessary if the insect population is heavy or nonchemical approaches fail. The following is a brief description of some of the common house plant insects and control methods which can be used.

Spider mites are tiny, spider-like creatures which require magnification to be seen clearly. They initially attack the underside of leaves and spread over the entire plant. Heavy infestations are characterized by the presence of webbing. They spread by leaf to leaf contact and on hands and clothing. Heavy feeding causes bronze or yellow leaves which may drop. Such infestations result in stunting and plant death. Washing the plant with a forceful water spray breaks the webs and dislodges the mites. If washing fails to control the mites, an insecticide can be used at weekly intervals as a spray or dip. Repeat the washing or spraying weekly for at least 3 weeks to control mites.

Mealy bugs are slow-moving, soft-bodied insects which appear to have been dusted with flour. They are about 3/16" long and may have waxy filaments extending from rear. Eggs are laid in clusters of white fuzzy material. They are found on stems and leaves, especially along veins. Strong measures are necessary to control mealy bugs. If one plant only is infested, try hosing with spray or use cotton swabs dipped in alcohol. Must be repeated every five days. Dip or spray badly infested plants with an insecticide every five days until there is no sign of insects. Add a mild detergent to the spray (1/2 tsp/gal water).

Fungal gnats are delicate, gray flies 1/8" long. They are attracted by lights and can be readily found in windows. The immature, whitish worm-like maggots live in very moist soil where they feed on decaying organic matter. Occasionally they may feed on roots. These insects are considered a nuisance since they cause little or no plant damage. The larvae can be controlled by reducing soil moisture. Allow the soil surface to become dry between watering. If this fails, insecticide can be applied to the soil. The adult flies can be controlled by using an aerosol household spray. If you would prefer not to use an insecticide, adding 1 teaspoon of white vinegar per pint of water when watering will give some control.

Springtails are small (1/15"), whitish or blackish, soil-inhabiting insects. They can have a globular or elongate shape and most can jump. Springtails thrive in moist soil rich in organic material. Large numbers can be seen on the soil surface, especially after watering. These insects are a nuisance pest since they cause little, if any, plant injury. They can be controlled by reducing soil moisture. Allow the soil surface to become dry between watering. If this fails, insecticide can be applied to the soil.  If you would prefer not to use an insecticide, adding 1 teaspoon of white vinegar per pint of water when watering will give some control.

Scale insects have shell-like coverings which protect a soft body. They are generally immobile and 1/16" - 1/8" in diameter, but may be larger. They can be various shapes and range from white to black with browns and grays predominating. They attack leaves and stems, particularly along leaf veins, sucking plant juices and causing poor growth and stunted plants. Scale insects produce a sticky, honey-like substance (honeydew) which can provide a medium for mold growth. Cultural control is washing or spraying the plant with water. If this fails, they can be sprayed with an insecticide at 3 - 4 week intervals. A mild detergent (1/2 tsp/gal water) should be added to the spray mixture. Putting the infected plant in a plastic bag for a day or two with an opened No-Pest strip can also control scales.

This page was last updated April 2003

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