The term ‘nats’ generally refers to diverse groups of small, winged insects. These tiny creatures can cause noticeable irritation through their bites. Understanding the biological reasons behind their biting behavior clarifies their impact.
Identifying the Biting Nats
The term “nat” is a general, non-scientific word that typically encompasses several families of small, biting flies. These include biting midges, also known as “no-see-ums” or “punkies,” black flies (sometimes called “buffalo gnats”), and sand flies. Biting midges are particularly tiny, often less than 1/8 of an inch long, making them difficult to spot. Black flies are slightly larger, around 1/5 to 1/4 inch, and often have a distinctive humpbacked appearance.
Despite their small stature, these insects possess specialized mouthparts capable of cutting skin. Their minute size allows them to pass through standard window screens, a trait that contributes to the ‘no-see-um’ nickname.
The Purpose Behind the Bite
The primary reason certain ‘nats’ bite is rooted in their reproductive cycle. Almost exclusively, it is the female insect that seeks a blood meal. This blood provides proteins and nutrients for egg development. Without a blood meal, the female may not be able to produce viable eggs or lay as many.
When a female bites, she uses scissor-like mouthparts to cut through the host’s skin, creating a small wound. Unlike mosquitoes, which pierce with a needle-like proboscis, biting gnats create an incision from which blood pools. The insect then injects saliva containing anticoagulant compounds into the wound. This saliva prevents the blood from clotting, allowing the insect to feed efficiently. The irritation, itching, and swelling associated with the bite are primarily a reaction to these injected salivary compounds.
What Draws Them In
Biting insects, including various types of ‘nats,’ employ a range of sensory cues to locate their hosts. A primary attractant is carbon dioxide (CO2), which humans and animals exhale. Insects can detect CO2 from significant distances, signaling the presence of a potential blood source. Higher CO2 levels increase attraction.
Body heat is another cue, as warmth indicates a living host. Sweat chemicals like lactic acid, uric acid, ammonia, and octenol also attract them. These compounds, produced during physical activity, are detected by their sensitive olfactory receptors.
Certain body odors, a result of skin bacteria interacting with sweat, also play a role in attracting these insects. Beyond chemical signals, visual cues are important; dark clothing can make individuals more visible and attractive to some biting flies, including black flies. This combination of sensory inputs guides the insects to their intended targets.
Strategies for Reducing Bites
Minimizing exposure to biting ‘nats’ requires understanding their behavior and applying practical measures. Since many species are active during dawn and dusk, avoiding outdoor activities during these peak times can reduce encounters. Wearing light-colored clothing can also make you less visible to biting flies drawn to darker hues.
Covering exposed skin with long-sleeved shirts and long pants provides a physical barrier against bites. Using insect repellents containing effective ingredients like DEET or picaridin can deter these insects. Natural options like oil of lemon eucalyptus, peppermint oil, or tea tree oil also repel them.
Avoiding breeding areas like standing water, swamps, marshes, or flowing streams can also help. Utilizing fans outdoors can be beneficial, as many of these small insects are weak fliers and struggle in windy conditions.