Why are blue bottles called bluebottles?

Blue bottles, or bluebottle flies, are named for their distinctive metallic blue coloration on their bodies. This striking hue is a key identifying feature of the species, which belong to the Calliphoridae family. The term "blue bottle" has been used since the 18th century and is thought to derive from their appearance, resembling a bottle's color. Additionally, the name may also reflect the flies' habit of being found around decaying organic matter, where they are drawn to the blue light emitted in certain conditions.