Lytta sayi, commonly known as the Say's blister beetle, is a species of insect belonging to the family Meloidae. It is found in various regions of North America, including the western United States and parts of Canada. These beetles are typically black or dark brown in color, with a long and slender body. They are known for their defensive mechanism of secreting a toxic substance called cantharidin, which can cause blistering and irritation on contact with skin.