Wednesday, 30 January 2013

January Flies

A cautionary note: if you are not particularly interested in flies, don't bother reading any further!

A sunny but breezy day at last brought out some flies, by which I mean diptera - House Flies, Blowflies and their kin.
Calliphora vicina, Byfield Pocket Park. 30 January, 2013

Sun-bathed tree trunks and fence posts in the Pocket park were occupied by Blowflies, all the specimens I took being examples of Calliphora vicina, probably the commonest fly in its genus. It is a robust insect with the jowls (the area beneath the eyes) distinctly yellow-orange. It will lay eggs on the tissues of living animals, upon which the maggots will then feed - a habit known as myiasis, but this species seems to confine its attacks to small mammals such as hedgehogs, especially when the body temperature is low and the creature is in a torpid state, as in hibernation. Some blowflies are now used in "maggot therapy", the maggots being applied to wounds, feeding on dead tissue and so cleaning up the area. A relative of Calliphora species, Lucilia sericata, is the most commonly used. In the same situation Dasyphora cyanicolor, a member of the House-fly family, was present in smaller numbers.

Also in the Pocket Park I swept an Escallonia shrub and was rewarded by a couple of Sepsis fulgens. Rather ant-like in appearance, Sepsid flies are sometimes called Scavenger Flies. S. fulgens, a species with black-tipped wings, is abundant around the dung of farmyard animals and, although it will feed on nectar, it also visits dung for protein, water and minerals. Identification is ticklish (the whole insect is little over 2mm long) but the fore-legs of the males are armed with various spines and protuberances to help separate the species; fortunately I took a male! Sepsid flies can often be seen in the warmer months walking around and waving their wings in the air and, unsurprisingly, it has been shown that this is part of a mating display. 

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