No-see-ums are tiny biting insects, also known as biting midges, sand gnats, or punkies. These minuscule pests belong to the scientific genus Culicoides. Measuring only 1 to 3 millimeters, their small size makes them difficult to see, leading to the common anxiety that the insect may have disappeared beneath the skin after a bite. Understanding their biology explains why the resulting skin irritation is severe and why the fear of burrowing is unfounded.
No-See-Ums Do Not Burrow
The concern that no-see-ums burrow beneath the skin is a common misunderstanding stemming from the intense, delayed itch of their bite. No-see-ums are temporary blood feeders. They land on the skin, take a quick blood meal, and immediately fly away. Their mouthparts are designed for cutting the skin and sucking blood, not for tunneling or establishing a permanent residence within the host.
This behavior contrasts sharply with true burrowing pests, such as the scabies mite, which actively tunnels beneath the surface to lay eggs. No-see-ums are airborne insects seeking a nutritional source for reproduction, and once the female obtains the blood required for her eggs to mature, she leaves the host entirely.
How the No-See-Um Bite Occurs
The diminutive size of these midges allows them to easily bypass barriers like standard window screens, making them difficult to avoid indoors. Biting is performed exclusively by the female no-see-um, who requires blood protein to complete her reproductive cycle. Unlike mosquitoes, which pierce the skin with a needle-like proboscis, the female midge uses specialized, sharp mandibles to cut the skin surface.
This slicing creates a small wound, allowing blood to pool just beneath the surface. As the midge feeds, she injects saliva containing an anticoagulant into the wound. This chemical prevents the blood from clotting, ensuring a steady meal flow. The pain from the initial cut is often felt as a sharp prick, but the more intense, noticeable reaction is usually delayed until the insect is gone.
Identifying the Symptoms of a Bite
The injection of the midge’s saliva triggers an immune response, leading to the characteristic symptoms of a bite. The most common reaction is the development of small, intensely itchy, red bumps or welts. Bites typically appear in random clusters on exposed skin, especially on the legs, ankles, and arms.
The size of the welts can vary significantly, sometimes swelling into spots up to one or two inches in diameter. The resulting irritation and itching can last for several days, and the welts may persist for up to two weeks. Scratching the bites damages the skin barrier, which increases the possibility of a secondary bacterial infection.