The common name of blow fly refers to the fly’s deposition of eggs and comes from antiquity with references dating back into the 16th century. The common name of bottle probably comes from “bot” which is an old term for maggot, thus bottle would mean a little maggot. These flies are more than just a nuisance, they are of medical importance because of their mechanical transmission of disease organisms and ability to cause myiasis (infestation of tissues/cavities) in humans and animals.
Adults are about 1/8-5/8” long, about house fly size or slightly larger. Their colours are partly or wholly metallic blue, green, or dull brassy and sometimes black. Blow fly’s disease carrying possibilities are often overlooked. Because many species feed on filth such as human excrement and sewage and/or develop in the carcasses of infected animals, these flies may easily infect food humans eat.
Most species develop in meat or animal carcasses, but if these are not available they will use animal excrement, decaying vegetation, and/or garbage. Dead rodents, birds, and other small animals can be the source of flies within structures while dog excrement and garbage are common outdoor sources.