Reproduction
The Calliphora vicina use dead flesh as a source of food for
their larvae to develop. For reproduction to occur the
female C. vicina must find a dead host or a piece of dead flesh
on said host (a wound of some sort). Before laying her
eggs the C. vicina search for a suitable part of the body for
her eggs to feed. (In J.H. Fabre’s study the female nuzzled her
eggs between the eye and the beak) The female sets her
ovipositor at right angle and deposits her eggs onto the
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carcass. The eggs are dispelled form her ovaries in continuous
flow for about 30 minutes. She will take several breaks in this
process in which she cleans the probe that she uses for placing
her eggs and rests aside the carcass. After a few hours of
this and the eggs have all been dispelled (about 300) the
mothers work is done and she will die within the day. The
eggs were in a layer going down the birds gullet (esophagus)
forming a white layer of them. In a few days the eggs will
hatch and the larvae will make their way into the body to feed
on the internal organs. The ovipositor can be extended to get
the eggs inside the body in the case that the fly notices a cut
or tear in the skin. In the absence of any way to get into
the body eggs will be laid in any area of the body with more
delicate skin such as the axillary or the groin (Fabre J.H. 1919).
Once the larvae have hatched and invaded the body they may begin
their digestive process. The C. vicina egg needs a high
humidity level in order to hatch. At first the larvae feed on a
fluid serum between the muscles fibers while excreting digestive
enzymes and ammonia, allowing for the dissolve of the muscle
tissues. Once digested enough the larvae lacerate the
product with their mouth hooks (Oldroyd H. 1964). The larvae are
generally found in cooler environments in the western European
region of the world. They tend to grow faster in warmer
environments (30 degrees C) (Greenberg, 1991) and do not survive
well in colder environments (-8 Celsius). While larger
larvae have a good chance to reproduce, they have about a 50%
chance to become crippled adults. The smaller flies only
have about a 28% chance to reproduce and a 98% chance of dying
before reaching their mature stage. (Saunders D.S.) The amount
of centralized C. vicina can affect their development as well.
Overcrowding may lead to a reduction in both the size of the
blow fly and the size of the population vs. those in less
populated areas. (Saunders D.S. & Bee A. 1995)
Go to the Interactions page to learn about how it coexists with other species