Insects. Have wings and fly. House flies are usually not a big problem, but other types can suddenly occur in great numbers inside (e.g., cluster flies, drain flies, blow flies, flesh flies). Gnats (pronounced “nats”) are very small and some can bite. Others are merely annoying. Small phorid flies are often found where sanitation conditions are not ideal. Fungus gnats can infest house plants.
Cluster flies closely resemble house flies but are larger and slower in their movements. They are dark gray with checkered black and silvery-black abdomens. A newly emerged fly has many golden hairs on its thorax which may be lost as the fly ages. The stripes on the thorax are not as prominent as on the house fly, and the wings of cluster flies overlap over the abdomen when at rest. The wings of houseflies do not overlap over the abdomen when at rest. Cluster flies, when crushed, may have an odor similar to buckwheat honey and, when gathered together, they may emit a ‘sickly sweetish’ odor
Adult fungus gnats are dark, delicate-looking insects, similar in appearance to mosquitoes. Adult fungus gnats have slender legs with segmented antennae that are longer than their head. Although a few species are up to 1/2-inch long, adults commonly are about 1/16 to 1/8-inch long. Wings are light gray to clear; the common Bradysia species have a Y-shaped wing vein. Fungus gnats are relatively weak fliers and usually are not found flying around indoors. They generally remain near potted plants and often run or rest on growing media, foliage, or litter.