CHAPTER III
SOME OTHER FLIES AND THEIR DIVERSE HABITS
Just as the common "house-fly" and the "lesser house-fly" are often in error regarded as the same species with an insignificantly small difference of size, so the identity of each in turn may be confused with several other species which are not uncommon, but they are all normally outdoor flies.
The chief of these is the excessively common stable-fly, Stomoxys calcitrans, whose generic and specific designations are well given, for they mean "sharp-mouth," "kicking," the latter word denoting the action of the tormented horse; it has a long, thin, stiff, skin-piercing, shining black trunk, furnished with two lancets. It is an eager blood sucker. In size and colour it rather resembles the house-fly, but anyone who is keen sighted will recognise it at once by its bayonet-like trunk, held projecting prominently in front of its head. It is much addicted to basking outdoors on sunny walls, but on the approach of darkness or of inclement weather it will occasionally seek shelter indoors. Its wing pattern rather resembles that of the common house-fly, as has been previously explained.
Round about dairy farms Hæmatobia stimulans, a fly slightly smaller than the stable-fly, with a striped thorax and a blood-sucking trunk, will often leave the cattle to assail humanity. A still smaller, somewhat hairy, muscid type of fly, Lyperosia irritans, is also a common aggressor of oxen throughout the summer.
Musca corvina, the raven-fly, is smaller than the house-fly; it has very distinct dark markings; the abdomen of the female is chequered, but that of the male has a black central stripe on a yellowish abdomen. It frequents gardens, parks, and meadows. It is much less prolific than the house-fly, with which it shares the sweat-fly pestering habit.
Cyrtoneura simplex is a little smaller and more common than the species last mentioned; its larvæ are bred in the dung of cows and other animals which it very severely pesters. However, many species of dung-bred flies do not in the least participate in the cattle-pestering habit.
The Anthomyidæ are a family of about 250 small and medium sized garden frequenting and country flies, mainly of flower and honey seeking habits. Nevertheless, some are dung-frequenting; none are blood-sucking, but several are cattle-pestering sweat-flies, which, even more pertinaciously than the house-fly, will circle round one's head and repeatedly buzz against one's face. Of these, the small Hydrotœa irritans and Hy. dentipes are amongst the worst offenders. A few of the Anthomyidæ are vegetarian garden pests; the larvæ of the cabbage-fly, the root-fly, the onion-fly and the celery-fly are, in some seasons, very destructive. The so-called "turnip-fly" is a small striped beetle of the same genus, Phillotreta, as the unstriped "flea-beetle" of the hop-fields. The larvæ of the majority of the species of the family of Anthomyidæ are, more or less, feeders on decadent vegetable matter, but some, like those of the genus Fannia, are preferentially feeders on dung. The female of the latrine fly, Fannia scalaris, so closely resembles the lesser house-fly that only the expert with a magnifying glass, after a careful examination, can tell which is which; the male differs from the male of the lesser house-fly by being without the yellowish patches on the abdomen.
There is a larger and less common muscid fly, with an ashy-grey body, but with reddish legs, named by entomologists Muscina stabulans, which not only in body colour, but also in the pestering habit, resembles the house-fly; its Latin specific name is rather objectionable as too suggestive of the common "stable-fly," which name belongs to Stomoxys calcitrans above-mentioned; its larvæ have been found in cow-dung, but they can also flourish on vegetarian fare.
The common blue-bottle is now named Calliphora erythrocephala (red-head), and it can be recognised by its reddish face and black hairs for a beard, whilst the less common blue-bottle, named Calliphora vomitoria, may be said to have a reddish beard upon a black face; the latter has the blue colour more evenly distributed over the abdomen, whereon the former has dark markings.
Polietes lardaria is a fly sometimes mistaken for the blue-bottle; its specific name is rather too suggestive of resemblance in habit. It may be recognised by its having four black stripes on the thorax, by its large white squamæ, and its tesselated glaucous abdomen; its wing pattern classifies it as belonging to the Anthomyidæ, whilst the true blue-bottles belong to the Muscidæ, and the grey blow-flies to a section (Sarcophagina) of the Tachinidæ.