There is a good chance that you will encounter one or all of these six common houseplant pests, so here is how to control them with least toxic measures. Note that insecticidal soap or horticultural oil should be sprayed on the underside of a few leaves as a test of the plant's sensitivity before being applied to the entire plant.
Aphids: Found in clusters on tip growth and flower buds, these small green, black, brown or orange insects can be dislodged with a strong spray of water in your tub or outside with the garden hose.
Mealybugs: These tiny white bugs appear as bits of cotton on stems or on the underside of leaves. Control them by apply rubbing alcohol to the leaves with a cotton swab.
Mites: Mite-infested leaves will be mottled or stippled, while flowers may be deformed and laced with a very fine webbing. A spray of water to both the tops and bottoms of leaves should control any mites still present.
Scales: Another hard-to-spot foe, scales leave behind sticky spot on plants leaves or on the tabletop. Rub off scales by hand if possible or spray all leaf surfaces with a light coating of horticultural oil or insecticidal soap.
Whiteflies: True to their name, they appear as a tiny cloud of white when a plant is touched or disturbed. Spray insecticidal soap on the leaves, especially on the underside for effective control.
Cats: Cats kept indoors express their inner feline by digging in potted plants or using them for litter boxes. If your cats won't stay away from your houseplants, crushed rue leaves spread on top of the soil will repel them.