Q: I brought in my houseplants and now the house is filled with fruit flies. They buzz around the kitchen and around the dinner table. When we brush by a plant, dozens of little flies swarm around. What can we do to get rid of them, short of throwing out the plants?
A: Let's start at the beginning and go back outside. Insect populations that were held in check outdoors by weather conditions, predators or parasites might expand rapidly indoors where conditions are more favorable. Also, plants that are in poor health are less able to resist insects. Insects that just used the flowerpots for shelter, but ventured out to feed are going to find less to eat around the pot and will have to start venturing farther afield into other places in the house to find food. The kitchen will be a great new territory to explore because of potential food sources.
In the fall, many insects begin laying eggs or go dormant in a pupa stage that is supposed to survive the winter. They may begin hatching after what will feel like a very short winter to them. You should inspect the leaves that remain on the plants to look for any insect problems. The closer the plants have been stored indoors, the more potential there has been for insects to transfer from one plant to another.
It might be a coincidence that fruit flies arrived on store bought or homegrown vegetables, (such as tomatoes or bananas that are often stored on the counter and not in the refrigerator) at the same time as the plants were brought indoors. It might be that the insects are not real fruit flies but one of the dozens of other tiny insects that inhabit plants, such as aphids or whiteflies.
Is the weather warm enough that you can take the plants back outdoors for a quick bath? Take them out and wash off the plant with a teaspoon of dish soap mixed in a gallon of lukewarm water. Or, spray the plants with an insecticide. If the plant is small enough to pull out of the pot, check the root system to see if it is harboring roly-poly pill bugs, earwigs, spiders and other creatures that you don't want indoors. You can flush the potting soil with the same mix of soapy water or an insecticide mix to get more creatures to crawl out of the pot.
If you can't take them outside, you can wash the plants in the shower. A quick blast of lukewarm water can wash many insects off the bottom of the leaves.
Back indoors, check to see if any of the plants are getting blasted by a warm air vent that will dry them out quickly. The leaves will dry out much faster than normal even if they aren't in direct sunshine. Plants near a cold draft from a window or door will also have problems. These dry conditions are great for spider mites and a host of other insects.
If you can't move them outdoors and even if you do wash them off, you can do one more treatment. Use a systemic insecticide, such as Bonide Systemic Houseplant Insect Control, available at your local garden center. These insecticides are available in granules, spikes and powders. They soak into the roots and move throughout the whole plant reaching the places that sprays and soap baths do not. It may take a couple of weeks to move through the whole plant, but they will work. They are especially good at getting the newly hatched insects before you notice them and before they can build up to large populations.
You might have to decide which plants are worth keeping and which ones are just so cheap that it isn't worth the time, effort or electricity of a grow light to try to keep alive all winter long.
Email questions to Jeff Rugg at [email protected] To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.