Biting midges are small, blood-feeding flies, often referred to as “no-see-ums,” “sand flies,” or “punkies.” These minute insects, typically 1-3 millimeters long, deliver painful bites. Only the female midges bite, requiring blood meals to develop their eggs.
Global Reach
Biting midges are found worldwide, on every continent except Antarctica. Over 4,000 species have been identified, with over 600 in North America alone. The genus Culicoides is the most widespread, inhabiting both tropical and cooler regions, and can be found up to approximately 4,000 meters above sea level.
These flies are prevalent in tropical, subtropical, and temperate zones with suitable humidity and water sources. For instance, they are commonly found in coastal areas and farming regions throughout the United States. Different species of biting midges are adapted to specific geographical areas.
Preferred Environments
Biting midges require specific environmental conditions for both their larval and adult stages. Larval stages develop in damp, organically rich habitats. These include muddy or sandy edges of ponds, lakes, and streams, salt marshes, mangrove swamps, moist decaying leaf material, tree holes, and rot holes.
Some species of biting midges prefer brackish water environments, such as tidal flats or salt marshes. Conversely, other species thrive in freshwater locations or moist soil around leaky pipes or septic tanks. Larvae consume decaying organic matter, algae, or detritus within these wet substrates.
Adult midges, when not actively feeding, often rest in dense vegetation, tall grasses, and shaded areas near their breeding grounds. They may also seek shelter indoors, even passing through typical window screens due to their small size. This preference for sheltered, humid locations helps them conserve moisture and avoid direct sunlight.
Seasonal and Climatic Influences
Environmental factors influence the presence and activity of biting midges. Temperature is a key determinant; the life cycle, from egg to adult, typically completes faster in warmer conditions. For example, eggs can hatch in 3-5 days in 80°F weather, while the entire life cycle can range from 2 to 12 weeks depending on species and temperature.
High humidity and sufficient rainfall create favorable breeding conditions by maintaining moist environments for larval development. Adult midges are also more active under calm, damp conditions, often biting around dawn and dusk, or throughout overcast days. Heavy rains can create new breeding sites, leading to an increase in midge populations.
Conversely, droughts can reduce suitable breeding habitats, potentially leading to a decrease in midge numbers. Biting midge activity is generally seasonal, with populations typically peaking during warmer months and being less active or absent during colder periods.