Sand flies are small, flying insects belonging to the family Psychodidae. They are typically found in warm, humid environments, often near beaches, marshes, and forests. Sand flies are most active during dusk and dawn, and their bites can be painful and itchy. These insects are known for transmitting diseases, including leishmaniasis, a serious illness caused by parasites. Sand flies are often mistaken for mosquitoes, but they are generally smaller and have a more robust body. Their presence can be a nuisance, especially in areas where they are prevalent.