Biting midges, belonging to the genus Culicoides, are persistent and annoying blood-sucking flies encountered by humans and animals worldwide. These tiny insects are frequently called “no-see-ums,” “punkies,” or “sand flies” due to their diminutive size and coastal habitat preference. Though they are true flies, many people mistake them for mosquitoes or gnats until they experience the sharp, burning sensation of a bite.
The Scale of the Insect
The defining characteristic of the biting midge is its size, which earned it the common name “no-see-um.” Adult midges typically measure between 1 and 3 millimeters in length, making them roughly the size of a pinhead. This small scale means they can easily pass through standard window and door screens. Their body structure is generally short and stout, sometimes described as having a slight hump-backed appearance. They contrast sharply with larger biting pests like mosquitoes, whose bodies are significantly longer and more slender.
Specific Visual Characteristics
Upon closer inspection, the body of the biting midge is often dark, ranging from dark gray to brown. A freshly fed female midge may appear reddish or dark orange as her abdomen swells with a blood meal. The body is covered in fine hairs, which contributes to their fuzzy, gnat-like appearance. The wings are a key feature for identifying the Culicoides genus; they are broad in relation to the body and frequently marked with distinctive patterns. These patterns are mottled or spotted with dark and pale areas, creating a grayish look that helps distinguish them from other small flies. Their antennae are relatively long, composed of 15 segments, and are visibly more feathery in males than in blood-feeding females. When at rest, the wings are typically held flat over the abdomen.
How They Puncture the Skin
The “biting” part of the midge’s name is due to specialized mouthparts designed for cutting rather than piercing. The midge possesses a short, downward-pointing proboscis that contains minute, scissor-like blades called mandibles and maxillae. These four cutting blades lacerate the skin and tear tissue to create a small wound, which produces the immediate, sharp pain felt by the victim. Once the skin is cut, the midge feeds on the small pool of blood that collects at the site, a strategy known as telmophagy. Only female midges possess these blood-feeding mouthparts and require a blood meal for egg development. Male midges lack the cutting apparatus and feed exclusively on plant nectars and saps.