No-see-ums, often referred to as biting midges, are minuscule insects that can cause significant discomfort. These tiny pests are barely visible to the naked eye, measuring only about 1 to 3 millimeters in length. Despite their small size, their bites can be quite painful, often leading to itchy welts that linger for days.
Understanding No-See-Ums
No-see-ums thrive in damp, humid environments, commonly found near water sources such as marshes, muddy areas, and even wet tree holes. Their life cycle involves four distinct stages: egg, larva, pupa, and adult. The entire process, from egg to adult, typically spans two to six weeks, depending on prevailing environmental conditions.
Female no-see-ums require a blood meal to produce eggs, which they then lay in moist substrates. The larvae are aquatic or semi-aquatic, feeding on organic matter in their damp surroundings. As adults, these insects are attracted to warmth, humidity, and the carbon dioxide and body heat emitted by humans and animals.
The Impact of Extreme Temperatures
Temperature plays a significant role in the survival of no-see-ums at all life stages. For their eggs, optimal hatching temperatures range between 70-80°F (21-27°C), while temperatures above 100°F (>38°C) are lethal. Larvae develop best between 65-75°F (18-24°C), but they cannot survive prolonged exposure to temperatures exceeding 95°F (>35°C).
Extreme heat harms insects by causing desiccation, which is severe water loss, and by denaturing proteins within their bodies. It can also disrupt cellular functions and damage components like mitochondria. For adult biting midges, upper lethal temperatures are typically around 104-105.8°F (40-41°C). Sustained exposure to these extreme temperatures ensures greater mortality.
Conversely, extreme cold is also detrimental to no-see-ums. Eggs and larvae do not survive temperatures below 32°F (<0°C). Adult biting midges have lower lethal temperatures around 21.2°F to 24.8°F (-6°C to -4°C). Freezing temperatures cause bodily fluids to turn to ice, rupturing cells and damaging organs. While some insects tolerate or avoid freezing, prolonged exposure to temperatures below their survival threshold is lethal.
Practical Temperature-Based Control Methods
Understanding how temperature affects no-see-ums informs practical control strategies. Indoors, a cooler environment deters these pests. No-see-ums cannot tolerate cold temperatures and low humidity; air conditioning is effective.
Setting indoor temperatures to around 65-70°F (18-21°C) makes the space less appealing and reduces humidity, which is crucial for their survival. Using fans, both ceiling and portable, also help. No-see-ums are weak fliers, and fan-created air currents make navigation and landing difficult.
Outdoors, reducing humidity by eliminating standing water and damp organic matter, such as decaying leaves, removes their preferred breeding grounds. While large-scale outdoor temperature alteration is not feasible, these methods create inhospitable environments.