Several common pests can infest your houseplants, but severe damage to plants is rare. Most indoor plant insects are tiny and difficult to see with the naked eye, so you might need to rely on other signs and symptoms to identify the pest. Some houseplant pests can also infest outdoor plants, while others seem to find it difficult to survive outside of the home environment. Most houseplant pests, however, are brought into homes when a new plant is purchased from a garden store or nursery. That's why it's so important to carefully inspect any newly purchased plant for diseases and insects before introducing it to your home.
Identify fungus gnats by their minuscule size and tiny black to dark-gray bodies. Fungus gnats fly or hover around indoor plants and the larvae feed on fungi in the potting soil. These indoor plant pests typically do little or no damage but their presence usually indicates that you're overwatering your houseplants.
Look for spots of sticky clear liquid called "honeydew" on the leaves of your indoor plants to identify an infestation of scale insects, especially soft brown scales. The scale insects are difficult to see and immobile, but you may detect them as small oval-shaped brown specks on the stems and leaves. Scales feed on the plant juices and exude the honeydew, which often attracts black sooty mold spores.
Spot whiteflies infesting your houseplants by looking for tiny white flying insects that tend to remain on the undersides of the leaves and take flight only when disturbed. Like scale insects, whiteflies also feed on the plant sap and excrete the sticky honeydew on the indoor plant's leaves.
Identify a spider mite infestation by noticing yellow speckling of the houseplant's leaves and fine web-like structures on the undersides. With a magnifying glass, you may be able to see tiny mites crawling on the webs. Spider mite infestations are most common when indoor conditions are dry and hot.
Look for tiny pear-shaped insects on the undersides of the houseplant's leaves to spot aphids. Aphids tend to cover the leaves with sticky honeydew and feed on the plant sap in clusters or groups, causing the foliage to curl and become distorted.
Identify mealybugs on your houseplants by looking for tiny cottony-white insects on the stems and leaves, feeding on the plant sap and also excreting sticky honeydew. Mealybugs are oval and pinkish with white, waxy coatings.