Sand fly bites typically look like small, red, itchy bumps similar to mosquito bites. Most clear up within a few days without any special treatment. However, the appearance can vary depending on the species that bit you, and in rare cases, a bite that doesn’t heal normally can signal something more serious like a parasitic infection.
The Typical Sand Fly Bite
A standard sand fly bite produces a raised red bump, usually smaller than a mosquito bite, that itches and may feel slightly warm to the touch. Sand flies tend to bite exposed skin, particularly the lower legs, ankles, feet, and arms. Because these insects are tiny (often just 1 to 3 millimeters long), you may not feel the bite when it happens, only noticing the marks afterward.
The bites often appear in clusters or groups rather than as isolated spots. This is because sand flies are weak fliers that stay close to the ground and feed multiple times in the same area. If you wake up with a scattering of small red bumps concentrated on your lower legs or feet, sand flies are a likely culprit, especially if you’ve been near sandy beaches, marshes, or tropical forests.
How the Bites Change Over Time
For most people, the redness and itching from a sand fly bite peak within the first day or two, then fade over the next few days. The bumps may stay slightly raised and pink for up to a week, but they generally resolve on their own without scarring.
Scratching is the main thing that changes this timeline. Breaking the skin opens the door to bacterial infection, which can turn a simple bite into a swollen, pus-filled sore that takes much longer to heal. If you notice increasing redness, warmth spreading outward from the bite, or yellowish discharge, that points to a secondary infection rather than the bite itself.
Chigoe Flea Bites Look Different
“Sand flea” is a term that sometimes gets used interchangeably with sand fly, but chigoe fleas are an entirely different creature. These tiny crustaceans burrow into the skin, usually on the soles of the feet or around the toenails. The initial bite looks like a small red bump, but over the following days the appearance changes dramatically.
Once a female chigoe flea begins laying eggs under the skin, the bump swells and turns white. A distinctive black spot often appears in the center of this white area, which is actually the rear end of the flea still exposed to the air. The surrounding tissue becomes inflamed and painful. Over time, the area can turn dark and crusty or break open into an ulcer. The flea lives in the skin for four to six weeks before dying and eventually falling out, and the wound usually resolves on its own after that point.
When a Bite Could Signal Leishmaniasis
The most important reason to pay attention to sand fly bites is the small risk of cutaneous leishmaniasis, a parasitic skin disease transmitted by certain sand fly species found in tropical and subtropical regions, parts of the Middle East, Central and South America, and the Mediterranean. Not every sand fly carries the parasite, but when one does, the bite site can develop into something very different from a normal bug bite.
Leishmaniasis sores typically develop weeks or even months after the original bite. They start as small bumps or firm lumps at the bite site, then slowly grow and transform into open ulcers. The classic appearance is volcano-shaped: raised, rounded edges surrounding a sunken crater in the center, often covered by a scab or crust. These ulcers are usually painless, which is one reason people sometimes delay seeking care. Some people also develop swollen lymph nodes near the sores.
The key distinction is timing and progression. A normal sand fly bite improves within days. A bite that instead grows larger over weeks, develops a firm nodule, or turns into a crater-like ulcer needs medical evaluation. Leishmaniasis is treatable, but it doesn’t resolve on its own the way an ordinary bite does.
How to Treat Ordinary Bites
For standard sand fly bites, the goal is simply controlling itch and preventing infection. Wash the area gently with soap and water first. A 1% hydrocortisone cream, available over the counter, is one of the most effective options for reducing both swelling and itching. For bites that are especially uncomfortable, a cream containing 4% lidocaine provides a numbing effect that takes the edge off quickly.
If you have a large number of bites, a colloidal oatmeal bath can soothe widespread itching more practically than applying cream to each individual spot. Cold compresses also help reduce swelling in the first day or two. Oral antihistamines can help if the itching is keeping you awake at night.
Preventing Sand Fly Bites
Sand flies are most active at dawn and dusk, and they’re poor fliers that stay close to the ground. Covering your legs and ankles during peak hours makes a significant difference. Treating clothing and gear with 0.5% permethrin, an insecticide that kills sand flies on contact, provides protection that lasts through multiple washes. You can buy pre-treated clothing or apply permethrin yourself to pants, socks, and boots. Don’t apply permethrin directly to skin.
On exposed skin, use an EPA-registered insect repellent containing DEET, picaridin, or oil of lemon eucalyptus. If you’re also wearing sunscreen, apply the sunscreen first and the repellent on top. Standard mosquito nets can help at night, but sand flies are small enough to fit through regular mesh, so look for fine-mesh nets specifically designed for sand fly protection, ideally treated with permethrin as well.