Houseplants can be invaded by pests when you introduce new plants into the home that have not been cleared of all insects. These infestations can cause a previously healthy plant to quickly turn brown and die off. While there are hundreds of different insects that can attack houseplants, there are a few common culprits every gardener must watch out for.
Spider mites produce white flecks on the underside of leaves or near leaf veins by feeding on the plant's sap. A telltale sign of spider mites is the light webbing they weave over your plant's leaves. Wash your plant thoroughly if you notice spider mites and spray a horticultural oil. However, a plant that is heavily infested must be thrown out as spider mites reproduce rapidly and are tough to control once they've taken hold of a plant.
Mealybugs suck the sap from your plants. These insects attach themselves at the plant's roots, stems or leaves and produce a soft, white, sticky matter. Your plants leave will drop prematurely until the entire plant dies away. Swab any mealybugs you see from the plant using an alcohol soaked cotton ball. Use an insecticide to protect the plant from any unseen populations.
White flies are small, gnat-like flies that pull sap from your plant and produce a sticky matter over the plant's leaves. The plant loses color and vigor until it slips away. Trap white flies by placing double-sided tape around the plant or simply vacuum any flies off of the plant. Use an insecticide containing pyrethrin to kill the rest of the population.
Thrips are extremely tiny insects that are able to fly through the screens on your windows. Usually the gardener does not realize there is a problem until plant damage appears. Thrips feed on the plant, causing pale spots to appear over the plant. Dark spots of excrement from the insects usually appear around the areas as well. At their worst, thrips transmit disease to the plant. It is possible to treat the visible areas with horticultural oil; however, infected plants generally must be removed from the home to avoid further transmission to other plants.
Aphids suck the plant's sap and emit a sticky residue over the surface of the leaves. They are extremely quick to reproduce and must be dealt with as soon as possible. Wash the plant with water and spray an insecticide to rid the plant of the aphids.