Only certain types of flies bite, as they possess specialized mouthparts to pierce skin and draw blood. Common house flies, for instance, are a nuisance but cannot bite humans. They have sponging mouthparts designed to soak up liquids. Biting flies, conversely, have piercing-sucking mouthparts, which are needle-like structures that penetrate the skin. This adaptation allows them to access blood meals.
Understanding Which Flies Bite
The ability of a fly to bite humans or animals is directly linked to the structure of its mouthparts. Non-biting flies, like the common house fly, possess soft, sponging mouthparts designed to absorb liquid food. These flies secrete digestive enzymes onto a food source, then sponge up the dissolved liquids. Biting flies, however, have evolved different mouthparts known as piercing-sucking mouthparts. These specialized structures are rigid and sharp, allowing the fly to cut or pierce through skin. They function like tiny blades or needles, creating a wound through which the fly can then feed on blood.
Identifying Common Biting Fly Species
Common biting fly species include:
Horse flies are large, with powerful wings and distinctively colored eyes, which can be green or black. They use scissor-like mouthparts to slice the skin, resulting in a very painful bite.
Deer flies are slightly smaller than horse flies. They are often recognized by their patterned wings and bright green or golden eyes.
Black flies, also known as buffalo gnats, are small and have a characteristic humpbacked appearance. Their bites can cause bleeding, itching, and swelling.
Biting midges, commonly called “no-see-ums” due to their extremely small size, are hard to detect but can inflict surprisingly painful bites. These tiny flies are frequently found near coastal or marshy areas.
Stable flies resemble common house flies in size and coloration, but they possess a sharp, piercing proboscis that protrudes forward. While they primarily feed on the blood of livestock like horses and cattle, they will readily bite humans and dogs. Unlike most biting flies, both male and female stable flies feed on blood.
Sand flies are small, hairy flies found in sandy, tropical regions. They can deliver a painful, pinprick bite.
Reasons Flies Bite and Their Effects
The primary reason certain flies bite is to obtain a blood meal, which is often crucial for the female fly’s reproductive cycle. Female biting flies require the protein and nutrients found in blood to develop their eggs. This biological necessity drives their biting behavior, as they seek out suitable hosts to feed upon.
When a biting fly punctures the skin, it can cause immediate pain or a stinging sensation. The bite site typically develops redness and swelling, often accompanied by an itchy welt or blister. In some cases, individuals may experience allergic reactions to the fly’s saliva, which can intensify the local symptoms. While most fly bites are more irritating than dangerous, larger flies like horse flies can leave small puncture wounds that may require cleaning to prevent secondary infections.
Preventing and Managing Fly Bites
To minimize the risk of fly bites, several preventative measures can be taken. Using insect repellents containing active ingredients like DEET or picaridin on exposed skin can deter biting flies. Wearing long-sleeved shirts and pants, especially in areas where biting flies are prevalent, provides a physical barrier against bites. Avoiding outdoor activities during peak biting times, such as dawn and dusk, can also help reduce exposure.
Ensuring windows and doors have intact screens can prevent flies from entering indoor spaces. For those spending time outdoors, particularly in wooded or marshy environments, covering exposed skin and using repellents is particularly helpful.
If a fly bite occurs, cleaning the affected area with soap and water can help prevent infection. Applying a cold compress can reduce swelling and discomfort. Over-the-counter anti-itch creams or hydrocortisone ointments can alleviate itching and redness. Individuals experiencing severe swelling, intense pain, or signs of an allergic reaction should seek medical attention.