Even the name of this fly Calliphora vomitoria sounds kind of disgusting, with the ‘vomitoria’ no doubt relating to its habit of regurgitating its food and then eating it again. But it is not really its fault, as we will see later. ‘Bluebottle’ sounds better, which is a description of its gleaming blue abdomen. It belongs to a family of blowflies called Calliphoridae, which are fairly familiar to most of us as they are fairly large and stoutly built with a loud buzz. Most breed on decaying animal matter, and thereby assist nature in its essential recycling regime.
There are 14 genera and 38 species within Calliphoridae according to The Royal Entomological Society of British Insects (2011 edition), some of which include some of the greenbottle flies. There are 1500 worldwide. Calliphora vomitoria is often confused with Calliphora vicini. They both look superficially very similar, except with closer scrutiny Calliphora vomitoria has pale ‘cheeks’ and the jowls, below and behind the eyes, are covered in yellow/orange hairs. These can be seen on some of the images in this blog if you look carefully, but particularly in the image below and the final image. Double click on them for a closer look. Calliphora vomitoria grows up to 10–14 millimetres (0.4–0.6 in) long
It is said that blowfly maggots can compete with a lion at the speed in which they can strip a carcass down to the bone. This is obviously a fallacy, but it does reflect on the extraordinary efficiency with which these insects consume body tissues. At the smell of purification the adults will come, often in packs, and the females lay their eggs on soft tissue or near open orifices. The resulting maggots will feed quicker in hotter weather, but finally they will pupate within the corpse to emerge as adult flies. Despite how much we may loathe them, especially when they enter our houses and buzz around our heads and our food, they are our friends in that they help to clean up after death has had its way. Yes, they can spread disease and make food inedible, and the adult flies also vomit up their food to slurp it back up again. But evolution has not made their digestion as straight forward as ours. Their stomachs simply cannot cope, so they have to take it a bit at a time, regurgitate, and then add a mix of digestive enzymes to help break it down and fit for their digestion.
Calliphora vomitoria can be seen all year round, but mostly from March to October. They are common and widespread in Britain, and can be found virtually anywhere.
As much as flies trouble us at our picnics buzzing around our heads and our food, as much as we revile them, they are intrinsically woven into the fabric of our lives, as they have been for many thousands of years. In forensic science they help establish a time of death. Some blowfly larvae from Lucilia sp. are used in maggot therapy to help cleanse wounds, removing necrotic tissue. The adults are very good pollinators. So here we have it in a buzz or two, despite some of their most horrible and terrible traits, there is a balance of where they do, do some good.
Let us finish on an interesting poem from Raymon Queneau, which just shows how flies and humans play a dance throughout life until death:
When one sees flies, one thinks: they came from maggots. When one sees men, one thinks, to maggots they will come.
Photographs taken in August 2017, rear garden, Staffordshire, England.