If flies are all over your flowers, either indoor or out, several common types may be the culprit. Measures other than insecticides can be taken to eliminate the flies. Not all flies are harmful, so you may want to leave them be. Depending on the flies, there are several reasons why they may be all over your flowers.
Fungus gnats resemble mosquitoes more than common flies. The larvae feed on the organic matter in the soil, possibly harming the roots in the process. Fungus gnats are more likely to be present in constantly wet soil. They are more likely in houseplants that are brought outdoors during the warmer months. To get rid of fungus gnats, replace the soil in potting plants. For all plants, allow the soil to dry out between waterings, clean up the organic debris on top of the soil and snip off decaying foliage. Trap fungus gnats with yellow sticky cards, available in nurseries or use a pesticide safe for plants, but adhere to the directions and warnings on the label.
Hover flies, also known as flower flies, are beneficial insects. They resemble bees more than common flies. They even pollinate flowers. Hover fly larvae eat aphids, scale, caterpillars and thrips, all of which damage plants. They are all over your garden because there are insects for them to eat and flowers to pollinate. Hover flies are good for your garden.
Whiteflies damage your plants, sucking sap from the leaves. They resemble tiny moths that are about 1/16 to 1/10 inch long. Whitefly infestations quickly spread. To get rid of them, clip off the foliage most infested and dispose of it. Also use yellow sticky fly traps or vacuum the insects. Insecticides often do not work on whiteflies, as they often build up a resistance to the chemicals, according to University of Missouri.
Shore flies look similar to fungus gnats but are distinguished by the presence of five, light-colored spots on their dark wings. Shore flies are similar to fungus gnats in other ways as well. Their larvae infest the soil and can damage plant roots. They also thrive in wet, decaying organic matter. Clean up the plant debris around your flowers and snip off the decaying leaves on your plants. Let the soil dry out between watering. If you use a pesticide, follow label instructions. You'll have to repeat applications because larvae are not usually affected by pesticides.