Blow Flies

family: calliphoridae
common names: blow flies, blue-bottle flies, blue bottle flies
hosts:
notes: Small to large robust flies, generally with a metallic blue or green abdomen and aristae of antennae plumose at tip. Larvae (maggots) breed in decaying flesh and manure. Screw-wormlarvae may infest living tissue (myiasis)

Agriculture and Agri-Food Canada Insect Identification Sheet No. 94 1986 Blow Flies Calliphora vicinia (Robineau-Desvoidy) — bluebottle fly Phaenicia sericata (Meigen) — green bottle fly Phormia regina (Meigen) — black blow fly These cosmopolitan flies are primarily scavengers that feed on dead animals, decaying vegetable matter or garbage. They also 'strike' wildlife and farm animals (especially sheep) that have sores or wounds or are soiled with manure.

Injury:

The maggots crawl over the animal's skin or into wounds, causing extreme irritation. Their feeding inflames the skin and flesh and, as they penetrate deeper, causes ulceration, eventual blood
poisoning and death through bacterial infection.

Life Cycle, Appearance and Habits:

The adult emerges from the soil in May or June. It is nearly twice the size of a housefly. The female lays her eggs on dead animals, injured live animals or exposed meat. Each female can produce up to 500 eggs in clusters of 20 or more. The whitish maggot is blunt at the rear and tapers towards the head, which has a pair of small, black mouth hooks for tearing flesh. The maggot also produces a saliva that can dissolve flesh, enabling it to feed aggressively. It becomes full grown in 5-8 days. It then burrows into the ground and pupates within a brown leathery case. The pupal stage may last 1-3 weeks in summer. There can be four to eight generations during the year. It overwinters in the soil as a full-grown larva or pupa.

Control: Since blow flies are attracted to dead animals, bury these deeply. Treat infested animals promptly. Avoid injuring sheep during shearing, and perform all docking and castration only during the fly's off season. Contact your provincial agricultural representative, or entomologist, for details. The most commonly used blowfly for fishermen's maggot is Calliphora vomitoria, a holarctic bluebottle species. The adults are shade-loving, do not normally fly at night, but there has been recordings on adult Calliphora flying and ovipositing in slaughter-houses at night. Adults of Calliphora can occur in the winter on sunshiny days. One female may lay 300 eggs in carrion. The larvae are carrion feeders, and at 27C(80F) they have the following life history.

Stage: Duration (range)

Egg 26 hours(23-29)

instar larva 24 — (20-38) Length: 3-4 mm
instar larva 48 — (43-54) Length: 5-8 mm
instar larva 60 — (48-96) Length: 10-14 mm
Prepupa 360 — (240-504) Length: 9.5-12 mm *
Pupa 14 days (11-18) Length: 9-10 mm

Total immature: 23 days (21-27)

C. vomitoria is a rural species, mostly in forest and mountains, where it can be common among refuse in human settlements in rural situations.

All Information is From:

Smith, K.G.V. 1986. A Manual of Forensic Entomology. The Trustees of the British Museum (Natural History). London.

Morten Staerkeby email: mostarke@darwin.uio.no

The following was last updated on the 16th of September 1995 by G.J.L.Ramel@exeter.ac.uk

Flesh-flies and Blow-flies (Calliphoridae)

The larva of these flies all live in, or feed on, carrion, recently dead animals, but only when it contains a high degree of moisture. Blow-flies got their name from the fact that meat that they had laid their eggs into was called blown as in blown up. Blow-flies like the Blue Bottle Calliphora vomitoria are highly attracted to thawed out or cooked meats and can be quite a nuisance in warmer counties than the UK. The Green Bottles Lucilia sp., are apparently attracted to a different set of odours than the Blow-flies and this is why they are often common outside but seldom come indoors. The largest members of this group are the marbled-grey Flesh-flies, like Sarcophaga carnaria. These are again often common outside but seldom come into a house, and though they too breed in carrion they give birth to live young larva rather than laying eggs.

Aside from feeding on carrion there are a number of flies which have taken to feeding on living flesh. Some of these are related to the common Green Bottle i.e. Lucilia sericata and Lucilia cuprina which lay their eggs in the damp ammoniated wool around the sheep's anus and the larva which start off eating the feces soon take to eating the sheep's flesh. Between them, these two flies are a serious pest of sheep from Scotland to Australia. These and others like them which attack a wide variety of animals, particularly in the tropics, are known as Bots or Bot-Flies. Even more painful are the Warbles or Warble-flies whose larva burrow beneath the skin, leaving only their anal spiracles exposed to the air such as Dermatobia hominis, the human bot-fly of South Africa, whose females lay their eggs on a mosquito or some other sort of biting (piercing) fly which carries the egg to its human host. In tropical countries most animals are attacked by some warble or another, even elephants and rhinos have their hides pitted with the pock marks left behind by the larva as they burrow out of the skin before falling to the ground to pupate. Adult Warble-flies are large and hairy and often look like Bumblebees.