“No see ums,” also known as biting midges, are tiny insects that cause significant irritation through their bites. These minuscule flies, often less than 1/16 inch long, are barely visible to the naked eye, leading to their common name. Found in various parts of the world, particularly in warm, humid environments, they make outdoor activities uncomfortable. Understanding what attracts these pests is key to avoiding bites.
Host-Specific Attractants
No see ums possess a keen ability to detect cues emitted by warm-blooded hosts for a blood meal. A primary attractant is carbon dioxide (CO2), which humans and animals exhale with every breath. They perceive the CO2 plume from a distance. Body heat also attracts them, as no see ums are sensitive to temperature and gravitate toward the warmth radiating from living beings.
Chemicals present in human sweat and body odor enhance their appeal. Lactic acid, for instance, which is produced during perspiration and exercise, is a known attractant for no see ums. Certain fragrances from perfumes, lotions, and other scented products can also draw them in. Dark-colored clothing also absorbs more heat and creates higher visual contrast, making individuals wearing such attire more noticeable and attractive to these heat-seeking insects.
Environmental Attractants
Beyond host-emitted signals, environmental conditions also attract no see ums. Standing water, even in small amounts, is crucial for their breeding cycle, making damp environments highly attractive. Female no see ums lay eggs in moist soil, mud, or wet sand near bodies of water like ponds, streams, and marshes, or even in damp areas around homes. These areas provide moisture for larvae development.
No see ums are most active during specific times of the day, particularly around dawn and dusk. During these periods, humidity is often higher and winds are calmer, creating favorable conditions for their flight and biting activity. Artificial light sources can also attract them, especially when combined with human presence in outdoor settings. Overcast days can also see increased activity, as these conditions mimic their preferred low-light environments.
Minimizing Your Appeal
Strategies based on no see um attractants can help reduce bites. Covering exposed skin with long sleeves and pants, especially during peak activity times like dawn and dusk, creates a physical barrier. Light-colored, loose-fitting clothing can also be beneficial, as dark colors attract them and loose clothing provides protection.
Applying insect repellents is another effective measure. Products containing DEET, picaridin, or oil of lemon eucalyptus deter no see ums. Fans in outdoor areas also help, as no see ums are weak fliers and struggle against strong air currents. Eliminating standing water sources around homes, such as clogged gutters, birdbaths, and leaky faucets, disrupts their breeding cycle. Fine mesh screens on windows and doors prevent them from entering indoor spaces, as standard screens often have holes large enough for these tiny insects to pass through.