Gardening Articles: Health :: Houseplants

What's Bugging Your Houseplants?

by Susan Littlefield

You may get a break from dealing with outdoor pests in most parts of the country during the cold months of winter, but in the warmth of your heated home, houseplants pests can still be a problem. Often these trouble-makers have hitchhiked in on plants that spent the summer outdoors. But they can also come in on newly purchased plants. At this time of year, when many of us are purchasing plants for holiday decorating or receiving them as gifts, it's easy to bring in some unwanted visitors as well.

It is always a good idea to give any plant coming indoors a thorough going over before it takes up residence with your other houseplants. Check under the leaves and along the stems of plants that summered outside before you bring them back indoors. You may even want to give them a couple of precautionary sprays with a mild insecticide like insecticidal soap just to be on the safe side. And if you can give them a spot at least ten feet apart from your other plants for a couple of weeks, you may keep a beginning pest problem confined and easier to treat.

When you buy new plants, give them a similar look-over before you bring them home. Pass over any with signs of insect infestation. And what should you be looking for? Some of the most common houseplant pests are spider mites, mealybugs, aphids, fungus gnats, and scales.

Spider Mites


Spider mites, which are spider relatives, not true insects, thrive in the hot, dry air of our heated homes. Although they're tiny, the feeding of these sucking pests on the undersides of leaves can cause a lot of damage to plants. Look for leaves that are stippled with yellow and, when the infestation is severe, leaves encased in fine webbing. Hold an infested leaf over a piece of white paper and tap it sharply; if you see tiny, moving, dark dots on the paper, this will confirm your identification.

If you catch a spider mite infestation early, you may be able to bring it under control by spraying all leaf surfaces with water from the kitchen sink sprayer every few days. For larger infestations, control mites with sprays of insecticidal soap or horticultural oil. Repeat treatment at least twice at five day intervals to make sure you mop up mites newly hatched from eggs. It's probably best to discard severely infested plants.

To help reduce the chances of problems with spider mites, keep the humidity high around your plants. Line a waterproof tray with pebbles and fill with enough water to come up about half the depth of the pebbles. Then set your plant pots on the pebbles. The evaporating water will raise the humidity level around the plants, but the pots won't be sitting in water.

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