👉 Polygrapha is a type of parasitic fly found in Europe, Asia, and North America. They are known for their ability to transmit diseases through bites, particularly West Nile virus. This parasite is transmitted from an infected adult female to an adult male by the bite of a mosquito. The term "polygraph" refers to the round or oval shape of the parasites' eggs, which can vary in size and shape based on their growth stage.