Controlling Houseplant Insects

Insects, mites, and a number of other related pests occasionally damage the flowers and foliage of houseplants. The most common are aphids, mealybugs, whiteflies, scale insects and spider mites. Pests such as fungus gnats, caterpillars, ants, millipedes and slugs usually cause more alarm than they do damage.

Prevention

The best way to prevent pest damage to houseplants is to avoid the initial infestation. Carefully inspect leaves, stems, and soil of newly acquired plants for the presence of insects, mites, and other unwanted guests. Similar inspections should be carried out before moving plants back into you home for the winter. Always isolate these plants for a week or two and watch then closely for signs of developing pest infestations.

If plants are to be repotted, use a commercially prepared, pasteurized potting soil to avoid introducing sowbugs, fungus gnats, springtails, and other soil inhabitants. Removing dead leaves and debris from plants and pots helps eliminate hiding places used by many pests.

Infested Plants

When handling infested plants, be extremely careful not to accidentally transfer insects and mites from one plant to another. Other non-chemical ways to eliminate unwanted pests include removing and discarding infested leaves or stems for small insects, or large pests such as beetles, caterpillars and slugs can be picked off by hand and destroyed.

Gently wiping the leaves and stems with cotton swabs dipped in rubbing alcohol is an effective means of controlling aphids or mealybugs, especially if they are not too abundant.

Another useful technique involves washing plants with soapy water. Always rinse the plants a few minutes after treatment to avoid soap injury to the foliage. For best results, repeat the washing procedure two or three time at five to seven day intervals to destroy any pests (especially eggs) missed during earlier washings.

When plants have extremely heavy pest infestations, disposal may be the best solution. If possible, take a cutting from a non-infested part of the plant and start again.

Insecticidal Control

In many cases, pesticide sprays offer the most practical way to control pests on houseplants. When treating plants, be certain the product is specifically labeled for both the pest and plant species. This is important because not all pesticides kill all insects, and some materials can damage plants. The pesticide label provides a list of plants and pests for which it is recommended. In many cases it also includes those plants known to be injured by the product.

To be safe, test-treat a few plants and look for signs of plant injury after two to three day. If only a few plants are to be treated, a commercial, ready-to-use insecticide spray specifically labeled for controlling insects on houseplants is probably the best choice. Follow label directions and reapply the product as directed on the label. Multiple applications will be necessary in most cases.

Any product you plant to use in the house MUST be labeled for use indoors.