The horsefly is an insect resembling a large bluebottle, sometimes as large as several centimeters, dark brown in color, sometimes with yellow tints. In contrast to the harmless male, the female of the species can sting, and feeds of the blood of certain animals. This sting can cause localized infection in people, taking the form of a red, sometimes painful spot. In most cases, no treatment is needed apart from disinfecting the area. In some cases, however, this sting can be responsible for severe reactions in people with allergies
. The sting can also, in rare cases, inoculate parasites
teeming in the blood.