Gnats and Bugs on Indoor Plants

Gnats

• Resembling mosquitoes, fungus gnats are tiny pests that measure 1/10 to 1/8 inch and appear in shades of orange-yellow or grayish black. The tiny pests are common in houseplants because they thrive in the moist, organic matter in pots. Although adult gnats do not cause much damage, the larvae feed on plant roots, causing a reduction in health and vigor. Because each female can lay between 100 and 300 eggs at one time, a few small gnats quickly turn into a full-blown infestation unless corrected. Adopting good irrigation practices prevents the critters from infesting your houseplants. Drench the soil with a biological insecticide containing Bacillus thuringiensis var. israelensis to kill the eggs in the soil, thereby preventing the occurrence of damaging larvae.

Scale

• Two main groups of scale insects damage indoor plants: soft scales and armored scales. The bugs pierce through the branches, stems and leaves of indoor plants and sap essential juices, causing discolored foliage and stunted plant growth. Armored scales also secrete honeydew that increases chances of sooty mold fungus. Scrape early infestations of scale with your fingernail. Although adult armored scales are slightly difficult to control, their larvae are easily killed with horticultural oil.

Mealy Bugs

• Tiny insects related to scales, mealy bugs are commonly found on leaf axils and lower leaf surfaces where they suck plant sap, causing stunted growth and even death in extreme cases. Some varieties of mealy bugs also feed on plant roots and secrete honeydew. Hand pick the bugs if they are few in number, or rub a cotton swab dipped in alcohol over infestations. In case of a heavy infestation, a homeowner has no choice but to discard the indoor plant.

Aphids

• Measuring less than 1/8 inch, aphids are tiny bugs that appear in a variety of shades, including brown, yellow and pink. Commonly found on the undersides of leaves or feeding on new growth, aphids suck plant sap, resulting in discolored foliage and stunted new growth. Similar to mealy bugs and scale insects, aphids also secrete honeydew that increases chances of sooty mold. Spray aphids with water, or rub cotton dipped in alcohol over infestations.

Whiteflies

• Whiteflies are tiny bugs with pale yellow bodies and white wings that measure 1/16 to 1/10 inch. Females lay eggs on the undersides of leaves that hatch into nymphs within a few days. The nymphs go through four stages of development before they become adults. At each stage, the damaging pests sap essential plant juices and secrete honeydew, causing yellowing or wilting leaves or premature leaf drop. Spray small infestations with neem oil, or use imidacloprid or acephate insecticide over large infestations.