|I have white residue (probably some sort of bug) on many of my houseplants in different rooms of the house - some are in a pot and some are in waster. I spray with soap and water spray but it still comes back. What do I do? I can't spray my african violets since you can't get the leaves wet. Most of these plants are on windowsills.|
|Without more descriptive details it's hard to determine what it is but here are some white possibilities for you to compare. I hope this info helps!
Scale insects may be flattened and brown, or thick, white, and covered with a waxy or woolly substance. They appear like small bumps on leaves and stems. Leaves of infested plants turn yellow, and the overall vigor of the plant declines. Like mealybugs, the young are mobile, while the adults tend to settle in one area to feed. Ficus and citrus are often attacked by scale.
Controls: Flicking or rubbing the scale off the twigs by hand or dabbing them with rubbing alcohol often controls small infestations. For larger populations, spray horticultural oil or neem oil to cover the shells and suffocate the scale. Scale insects may hang on the twigs and leaves even after they are killed.
Whiteflies are tiny, white insects feed in large numbers on leaf undersides, sucking out plant juices. They secrete honeydew that may cause the growth of a sooty, black fungus on leaves. Their feeding can cause leaves to turn yellow and drop. They are easily disturbed and fly around when you brush against an infested plant. They are often found on hibiscus and ivy.
Controls: Whiteflies are attracted to the color yellow, so you can trap them by hanging yellow cards coated with a sticky substance, such as Vaseline, around your plants. Or suck them up with a vacuum cleaner as you shake your plants. In serious cases, spray plants with insecticidal soap, neem oil, or horticultural oil.
These soft-bodied insects group in white cottony masses and suck sap from plants. Their feeding weakens the plant and causes leaves to shed. Like aphids, they excrete large amounts of sticky honeydew. While adults tend not to move once settled on a leaf, flower, or stem, the young (crawlers) can move around the plant. Mealybugs favor cacti and jade plants.
Controls: For small infestations, wash the leaves in a shower to dislodge the insects, or dab individual mealybugs with a cotton swab doused in rubbing alcohol. The alcohol will desiccate the insects, killing them. For larger infestations, spray with insecticidal soap, neem oil, or horticultural oil.