A perfect day at the beach often includes sun, sand, and surf, but persistent, biting flies can quickly turn a relaxing outing into a frustrating experience. These insects leave behind intensely itchy welts and disrupt the peaceful environment. Multiple species of flies inhabit coastal zones, and each one presents a different nuisance. Understanding which pests are present and why they bite is the first step toward effective prevention and relief.
Identifying the Main Culprits
The biting insects most commonly encountered in coastal environments belong to three distinct groups, each with unique characteristics. Biting Midges, also known as “No-See-Ums” or Sand Flies, are the smallest, measuring less than 1/16 of an inch in length. Their minute size allows them to easily pass through typical window screening. They generally breed in moist sand, mud, and decaying debris near salt marshes or the water’s edge, and are most active during the low-light periods of dawn and dusk.
A second group, Horse Flies, are much larger, sometimes measuring up to an inch or more in length. Many species are powerful fliers with brightly colored eyes, and some coastal varieties are commonly called “greenheads.” Their relatives, Deer Flies, are slightly smaller, generally around 1/4 inch long, and often have dark bands across their wings. Both Horse Flies and Deer Flies are strong, aggressive, and tend to be active during the day, particularly in warm, sunny weather.
Why Beach Flies Bite
The aggressive biting behavior is directly tied to the reproductive cycle, as almost exclusively the female fly seeks a blood meal. Female flies require the protein and nutrients found in blood to successfully develop and lay their eggs, a process known as oviposition. Male flies pose no threat to humans and typically feed only on nectar or plant sap.
The mechanism of the bite varies significantly between species, explaining the differing sensations of pain. Horse Flies and Deer Flies possess specialized, scissor-like mouthparts used to slice into the skin. This cutting action creates a small pool of blood that the fly then laps up, resulting in a sharp, immediate, and painful sensation. Biting Midges, due to their smaller size, have shorter mouthparts and inject saliva that triggers an allergic response, often resulting in delayed, intense itching and swelling.
Flies locate their hosts through sensory cues, including body warmth, movement, and exhaled carbon dioxide. This attraction to movement is why Horse Flies and Deer Flies often swarm people walking or running near marshy areas. The persistent nature of these pests is simply a biological imperative driving the female to secure the necessary nutrition for her offspring.
Avoiding Bites and Repelling Pests
Minimizing contact with coastal flies relies on behavioral changes and the use of effective insect repellents. One strategy is to modify clothing choices, as flies are visually attracted to dark objects and moving targets. Wearing light-colored, long-sleeved shirts and pants provides both a physical barrier and a less attractive visual target. Additionally, avoiding the edges of marsh grasses or standing water, which serve as fly breeding grounds, can reduce exposure.
Timing can also influence the number of bites, as Biting Midges are most active around dawn and dusk. Applying a repellent containing a proven active ingredient is the most reliable chemical defense. Both DEET and Picaridin are recommended for effectiveness against a wide variety of biting insects. Picaridin, often formulated at 20% concentration, is a synthetic compound that is typically odorless and does not damage plastics, making it a good choice for beach gear.
DEET is considered the long-standing standard, blocking the insects’ ability to sense the carbon dioxide and lactic acid emanating from the skin. For non-chemical control, Biting Midges are susceptible to air currents. Bringing a small, portable fan can create a localized breeze that discourages them from landing. Reapplication of any repellent product is necessary, especially after swimming or excessive sweating, to maintain the protective barrier.
Treating Bites and Relieving Symptoms
When a bite occurs, immediate and proper care can significantly reduce the severity of the reaction and prevent complications. First, gently wash the affected area with mild soap and water to clean the wound and minimize the risk of secondary infection. Applying a cold compress or an ice pack can reduce localized swelling and provide a numbing effect that relieves immediate discomfort.
To manage the intense itching characteristic of these bites, over-the-counter topical treatments are effective. Anti-itch creams containing hydrocortisone or lotions such as calamine can be applied directly to the site to soothe the irritation. Oral antihistamines can also be taken to address systemic swelling and allergic reactions. It is important to resist scratching the bite, as breaking the skin increases the chance of a bacterial infection.