Most Common House Plant Pests

Aphids

Aphids are extremely small insects, growing no larger than 1/8th of an inch. They’re often a shade of green but this can vary. Aphids are usually wingless, but may develop wings they are moving from one plant host to another. Aphids feed using sharp mouthparts that they employ to suck out plant sap. Plant sap has valuable nutrients, so plants with aphid damage will sometimes have discolored leaves. Aphids often congregate in groups under leaves. You may also be able to detect aphids by the presence of the stick y honeydew they produce.

Thrips

Thrips are even smaller than aphids only about 1/16th of an inch and slender, with a tan or brown color. Their damage can also be seen in the form of discolored leaves, but with thrips, the discoloration is usually in silvery streaks or splotches. Flowers may also appear streaked. Thrips feed by using their mouthparts to scrape leaves or flowers, and then feeding on the fluid that is released. Adult thrips can fly, and so one way to detect them is to use yellow or blue sticky cards to capture these flying adults.

You may note that thrips and aphids are not common household plant pests, unless the plant was brought in from being outside.

Whiteflies

Like thrips, whiteflies are usually about 1/16th of an inch. As the name suggests, whiteflies are a light, white color. They resemble gnats and are mostly found on the underside of leaves. Younger whiteflies are more difficult to spot because they don’t fly yet and thus don’t flutter up when a plant is disturbed, like the adults do. But all stages of this pest feed on plant sap. Signs of whitefly damage include: the yellowing of leaves and premature leaf drop. While this is extremely similar to aphids and thrips, the key difference is the ability to find the whiteflies. They will generally congregate in large masses, making them easy to see on leaves.

Spider mites

Spider mites are usually not visible with the naked eye. Because of their small size, you’d usually need a magnifying glass or other means of magnification. Spider mites feed on sap using sharp mouthparts. This may cause a stippled appearance on leaves, or yellowing discoloration. (Severe damage can result in leaves looking bleached.) If you aren’t able to see spider mites but suspect your plant has them, you can try tapping the plant over a white piece of paper and watching for small moving creatures. Spider mites might also cause webbing—hence the name spider mite.

Fungus gnats

Fungus gnats are dark with clear wings, usually only about 1/8th of an inch. Unlike the other pests on this list, fungus gnats live in houseplant soil. There they can feed on decaying roots and fungi in the soil. Fungus gnats don’t usually cause much damage, unless they chew through new roots, and more than anything are a nuisance to the plant owner. Fungus gnats can sometimes be confused for fruit flies.

Scale insects

T o the untrained eye, scale insects might not even look like insects. That’s because adults live under hard, waxy shell-like coverings— giving them the appearance of scales. Underneath these coverings, scale insects are able to feed on plant sap causing yellowing leaves or, in severe cases, slowed and stunted growth. Soft scales produce honeydew.

Mealybugs

Mealybugs are most distinguishable based on the white, powdery substance that covers their bodies. They are usually about a quarter of an inch long. You can also tell if it’s a mealybug because they’ll sometimes have long white filaments sticking out the sides and rear of their bodies. Mealybugs feed on plant sap. Damage is usually in the form of discolored, yellow leaves, wilting plants, and/or honeydew.

Tips for prevention

• Check your plant before buying or before bringing it into your home. Particularly, looking for scales, mealybugs and whiteflies.
• Don’t overwater or underwater. Keep your plant healthy—plants in crisis are more likely to attract pests.
• Know the signs to look out for based on the pest, such as yellowing leaves or wilting plants.
• Use fresh potting soil when potting new plants.
• Clear dead leaves , branches, and stems and keep your plant clean of dust.