Gardening: Watch out for pests on indoor plants

With our outdoor plants now properly covered with a blanket of snow, it’s time to turn our attention to our houseplants and the bugs that can infest them.

Common houseplant pests include aphids, mealy bugs, fungus gnats and scale. How they find their way onto our plants varies from infected new plant purchases, as hitchhikers on plants that spend their summer outdoors or live under poor growing conditions.

Here’s what to know:

Aphids are about 1/16th- to one-eighth-inch long with greenish, pear-shaped bodies and visible legs and antennae. Aphids inflict their damage by sucking on plant juices. Severely infected plants will have yellow leaves, and the plants become stunted and distorted. The aphids exude honeydew, which supports a black, sooty mold. Aphids tend to hang out in clusters on stems near flower and leaf buds. They are best controlled by a washing in the shower or by rubbing the plant with a cotton swab dipped in alcohol. If necessary, pyrethrins, insecticidal soap or neem oil can be applied to the plants.

Mealybugs are soft-bodied insects about 3/16th-inches long. Characteristically, they look like tiny cotton balls covered with threads sticking out of their bodies and surrounded by a white residue. Like the aphid, they feed on the plant’s sap on the underside of the leaves and exude honeydew that attracts sooty mold. Heavy infestations will discolor leaves and cause stunting. They are best controlled by rubbing them with a cotton swab dipped in alcohol or spraying them with organic pyrethrins.

Fungus gnats are more of a nuisance than a plant damaging pest. They are about 1/16th- to one-eighth-inch long, dark colored with clear wings. They tend to fly around plants and in doing so, annoy you like a fruit fly would. Fungus gnats scavenge dead plant tissue and fungi in the soil of overwatered plants. They are best managed by letting the soil surface dry out between waterings. A layer of coarse sand applied to the soil also reduces access to overwatered soil. Control larvae by applying Bacillus thuringiensis, subspecies israelensis, strain AM 65-52 (e.g., the product Knock Out Gnats) to the soil. Plants can also be repotted in fresh soil and a clean container to remove the overburden of dead plant material and fungi.

Scale insects often look like tiny, brown, gray or white shells on the underside of leaves. They are about 1/16th- to one-eighth-inch in diameter. Both the larvae, which are mobile, and the stationary adults feed on plant juices, causing leaves to yellow and eventually drop off the plant. They can be removed with a fingernail or sprayed with horticultural oils, insecticidal soaps or pyrethrins to break down the shell.

White flies are usually noticed when they fly out from the underside of disturbed leaves. Only about 1/16th-inch long, the white, gnat-like insect feeds on plant sap and cause leaves to discolor and drop. They are best removed by washing the plant or applying insecticidal soap.