Question: I have fruit flies all over my houseplants. How do I get rid of them?

I am not sure if you are describing fruit flies or fungus gnats. You will have to look closely at one that is dead. I will describe both types to you. Identification is important so you know how to proceed in getting rid of these pests. Since you have found them around houseplants, I suspect they are fungus gnats.

Fruit Flies: (Drosophila melanogaster) Fruit Flies are small, about 1/8th inch long with a brownish body and a dark colored abdomen. Fruit flies typically have red eyes which help distinguish them.

Fruit flies are flying insects that are drawn to overripe fruit, vegetables, rotting plants and standing water. They can also be drawn to a variety of other sources, such as soft drinks, wine, and beer residue in unwashed containers that have been sitting around and trash containers with wet garbage that are not cleaned regularly. Also known as, pomace flies, kitchen gnats, or vinegar flies, they can lay hundreds of eggs at once and infest a kitchen quickly. They can be a common insect in homes during fall.

The best control of these flies is to find the source of the infestation and remove it. It may be tempting to kill the adults by spraying, swatting or trapping them but this rarely eliminates them. As long as a food sources remains, fruit flies can reproduce faster than you kill the adults.

Fungus Gnats: The darkwinged fungus gnat (family Sciaridae) is a common indoor fly. This mosquito-like insect is a very small, about 1/16th inch long, slender dark-colored fly with very long legs.

Fungus gnats are common pests of houseplants, particularly overwatered ones, where they feed primarily on decaying or damaged roots. They also can be found in houseplants growing in potting soil high in organic matter such as peat. They usually are a nuisance pest as adults, eating very little but laying many eggs in the soil of your favorite houseplants. They spend most of their life as larvae, eating organic matter and young roots. If you find gnats around your houseplants: Let plants dry between watering and throw out any weak and dead plants. If plants are too wet, use a fan to dry out the soil surface. This may deter the weak-flying adults. You may need to repot the plants in high-quality soil, eliminating existing eggs and larvae by gently washing the plant roots before you repot.

You can also set out yellow sticky cards with adhesive (purchase at garden centers). The yellow coloring attracts flying insects. They can be purchased and affixed to a Popsicle stick at the edge of the pots. To detect the larvae, place a small cut of potato on the soil surface for a day or two.

Note: treatments need time to work. An adult female can lay hundreds of eggs. Three to four weeks are needed to drastically reduce a fungus gnat population. If you choose to treat with a pesticide, please read and follow label directions of all pesticides.