The Q&A Archives: Indoor Plant Pests

Question: How do you control what seem to be small black gnats on houseplants?

Answer: The most common insects that prey on house plants are <br>aphids, mealybugs, mites and scales. I control these<br>insects by spraying a fine mist of rubbing alcohol on the plants using a fine-mist atomizer. Try a small section at first then wait a few days, to check for damage to the leaves, before spraying an entire plant. Insecticidal soap is another option. Be sure to spray the undersides of the leaves. <br><br>If the insects you see congregate on or near the soil and look like fruit flies, you may have fungus gnats. Sometimes these can be controlled with judicious watering--letting the soil dry out a little more between waterings so that the surface dries. (Don't go so far as to underwater the plants though.) Or you might try a product called "Knock-Out Gnats", available through Gardens Alive (5100 Schenley Pl., Lawrenceburg, IN 47025, ph# 812-537-8650). This is a biological control using a naturally-occuring bacteria specific to this pest. Or you might try yellow sticky traps (also available from Gardens Alive) to trap the gnats.<br><br>Often insects are brought in with plants that have been<br>outside and then are brought back inside. It is a good idea to rinse your plants before they are brought inside after<br>being outside. Just douse them in a container full of<br>water large enough to accomodate the plant.

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