Gnat

"Gnat" is not a single scientific group but a broad, informal common name applied to many small, slender flies within the order Diptera, spanning several families including biting midges, black flies, fungus gnats, and eye gnats. What they share is a tiny body size, delicate build, and a tendency to appear in loose swarms, particularly near water, moist soil, or decaying organic matter.

Some gnats, such as biting midges (often called "no-see-ums"), have piercing mouthparts and feed on the blood of animals, while many others, including fungus gnats and most swarming gnats, feed only on nectar, plant fluids, fungi, or decaying organic material and do not bite at all. This mix of feeding strategies means the word "gnat" alone does not tell you whether a given insect bites, making close observation of the specific type important for accurate identification.

Despite their small size, gnats play meaningful ecological roles as decomposers, pollinators of certain small flowers, and as an abundant food source for spiders, dragonflies, birds, and bats.

• Very small, slender-bodied flies, generally under 5 mm, with a single pair of functional wings (a hallmark of true flies, order Diptera).
• Long, thin legs and thread-like antennae, often longer and more delicate in males.
• Coloring is typically dull gray, brown, or black, though some biting midges have subtly patterned wings visible under magnification.
• Behavior varies by type: some hover in loose mating swarms at dusk, while others land repeatedly on skin or hover near the face and eyes.
• Lookalikes among the many "gnat" types include fungus gnats (associated with damp soil and houseplants), fruit flies (rounder body, associated with ripe produce), and mosquitoes (larger, with a long piercing proboscis).

Gnats as a group are found worldwide, with different types favoring different microhabitats: biting midges and many swarming species breed near standing or slow-moving water, marshes, and damp soil, while other gnats are drawn to moist organic debris, compost, and overripe fruit. They are most active during warm, humid months, particularly at dawn and dusk, and can appear indoors when moisture-rich conditions such as damp potting soil or drains provide a breeding site.

Feeding habits vary widely across the many insects grouped under "gnat": biting midges use piercing mouthparts to feed and can bite in search of a blood meal, while many other gnats feed on nectar, plant sap, fungi, or decaying organic matter and do not bite. Many species form loose aerial swarms, especially males, as part of mating behavior, often visible as a shifting cloud hovering over a lawn, doorway, or path at dusk. Ecologically, gnats and their larvae contribute to decomposition and nutrient cycling in damp soil and organic debris, and adults serve as an important food source for insectivorous birds, bats, and other predators.

Eggs are typically laid in or near moist environments such as standing water, damp soil, or decaying organic matter, and the larvae that hatch are small, worm-like, and legless, feeding on organic material, algae, or fungi depending on the species. Larvae undergo complete metamorphosis, passing through several molts before forming a pupa, from which the winged adult eventually emerges. Development from egg to adult can be very rapid in warm, moist conditions, sometimes just one to two weeks, allowing multiple overlapping generations throughout the warmer months.