Gnats are small, common flying insects often encountered in homes and gardens. Distinguishing them from other tiny flies can be challenging due to their similar appearances. This guide outlines what gnats look like and highlights visual cues to differentiate between various gnat species and other small insects.
Common Physical Characteristics of Gnats
Gnats are tiny insects, measuring around 1/16 to 1/8 inch (1.5 to 4 millimeters) in length, comparable to a grain of rice or a pinhead in size. They possess slender, elongated bodies, dark in coloration, ranging from black, brown, or gray, though some species may appear translucent. Gnats have six long, spindly legs that contribute to their delicate appearance.
Their wings are clear or slightly smoky, held flat over their bodies when at rest. Gnats have two pairs of wings, with the hind wings reduced to small, club-like structures called halteres. They also feature thread-like antennae on their heads, which are segmented and often longer than their head.
Visual Differences Among Common Gnat Species
Several common gnat species exhibit distinct visual characteristics that aid in their identification.
Fungus Gnats
Fungus gnats are slender, dark, delicate-looking flies, gray to black, with long legs and antennae that are longer than their heads. Their transparent or smoke-colored wings display a visible Y-shaped vein pattern. These gnats are weak fliers and tend to remain near potted plants or moist areas.
Drain Flies
Drain flies, also known as moth flies or sewer flies, have a fuzzy, moth-like appearance due to their bodies and wings being densely covered with fine hairs. They are brown, black, or gray, measuring 1/16 to 1/4 inch long. Their broad, rounded wings are held roof-like over their bodies when at rest, and their antennae are segmented and furry.
Biting Midges
Biting midges, sometimes called “no-see-ums,” are exceptionally small, barely visible, measuring only 1-3 millimeters. These robust-bodied gnats can be gray or reddish when engorged with blood, and many species have wings with dark and pale spots. Their minute size allows them to pass through window screens, making their presence noticeable primarily through their bites.
How Gnats Differ from Other Small Flies
Gnats are frequently confused with other small flying insects, but key visual differences can help distinguish them.
Fruit Flies
Fruit flies have a rounder, stouter body shape compared to the more slender gnat. They are tan or brown and possess prominent reddish eyes. Fruit flies also exhibit a slower, hovering flight pattern, distinct from the more direct flight of many gnats.
Small Mosquitoes
Mosquitoes possess a long, needle-like proboscis extending from their head, used for biting, which gnats lack. They also have distinct scales on their wings and bodies, and many species display stripes on their abdomen or legs. Mosquitoes assume a hunched-back resting posture, and their legs are longer than those of gnats.
Phorid Flies
Phorid flies, sometimes called humpbacked flies or scuttle flies, are characterized by a distinctive “humped” back when viewed from the side, which sets them apart from most gnats. These flies are tan to dark brown and are known for their erratic, scuttling running movement across surfaces rather than continuous flying. Their wings also have unique venation, with heavy veins near the leading edge and lighter, unconnected veins elsewhere.