Simple Ways to Combat Pests on Plants

Insect pests start building up on houseplants, especially this time of year. Pesticides are dangerous enough used outdoors; indoors, they are doubly so, because of the close proximity of plants to humans and pets. Fortunately, most insect problems on houseplants can be pinned on a handful of culprits that usually can be controlled without resorting to pesticides.

First, who are the culprits? Aphids are common, clustering usually at stem tips and making them curl up and die. Whiteflies make their presence known when they puff up as a cloud of little white “moths” whenever the leaves of an infested plant are disturbed. Whiteflies, like aphids, suck plants’ juices and can weaken plants to the point of death.

Less mobile on plants than whiteflies and aphids are scale insects and mealybugs. These insects find a nice spot, settle down, then just sit there and feed. Once they form their protective armor, scale insects look like blisters on the undersides of leaves or on the bark. Mealybugs look like dabs of cotton.

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Mites are not really insects, but arachnids, related to ticks and spiders. But they do feed on houseplants, increasing in number especially when the air is dry, as it is indoors this time of year. Mites are very small, just barely visible to the naked eye. Attacked leaves gradually take on a bronzed appearance as the mites destroy the chlorophyll in the plant. In severe infestations, tiny cobwebs became evident on the undersides of the leaves.

All these pests are easier to control before an infestation becomes severe, so check plants periodically. An occasional shower for houseplants washes some pests off before they gain a foothold, provides an environment inimical to others, and makes plants healthier by cleaning the dust off their leaves. Graduate to soap and water if pest problems escalate. You can buy insecticidal soap for this purpose.

A burgeoning population of whiteflies can be kept under control by trapping. The whiteflies’ attraction for the color yellow can be turned into a fatal attraction if yellow-painted cards or wide row markers coated with something sticky like Vaseline are placed next to infested plants.

Hand-to-hand combat can be effective against mealybugs and scale insects. Scrape off scale insects with your fingernail. Scale insects or mealybugs can be killed with a dab of cotton swab that has been dipped in rubbing alcohol.

Pests often spread from infested plants to nearby uninfested plants. If a plant is not particularly valuable and is severely infested, consider just discarding it rather than threatening other plants with its presence.