The more typical Flies have usually shorter and broader wings, and thicker, shorter, and more hairy legs, than those just mentioned; and the antennæ have usually only three or four joints, and are often furnished with a long, slender bristle at or before the end of the last joint.
As in the case of the Gnats and Crane-Flies, so as regards the more typical Flies, we have only space to notice a few of the more important families.
Some of the Gad-flies are no larger than house-flies, but others are as large as wasps or larger, with broader wings, and of a black, grey, or yellowish colour; they frequent fields, and settle on cattle, or on our clothes or hands. Some have transparent and others dark-coloured wings, but they are all capable of inflicting a severe puncture, often sufficient to draw blood, even in the case of the smaller species.
Photo by W. P. Dando, F.Z.S., Regent's Park.
BLUE-BOTTLE FLY, OR BLOW-FLY.
These flies deposit their eggs on meat, when it becomes "fly-blown."
The prettiest of the gad-flies are the Golden-eyed Flies. They are black, with the abdomen more or less marked with yellow; and black, or black and transparent, wings. The eyes are of a beautiful golden green, dotted and lined with purple. They are moderately stout insects, about the third of an inch long, and are not uncommon. Another insect, known as the Blood-sucking Rain-fly, has a rather long and slender body for a gad-fly, and is nearly half an inch long. It is of a lighter or darker grey, with reddish markings on the sides of the abdomen in the male. The wings are greyish brown with whitish dots, and a white mark towards the tip. Both these flies are very troublesome, the latter chiefly on the edges of woods or near water, especially in rainy weather.
The Robber-flies are large flies, with long, tapering bodies, of a black or partly yellow colour, and feed on smaller flies and other insects of different kinds. They have very thick, hairy and a strong proboscis. A handsome Australian species, allied to these, but with a broader body, is represented in the Coloured Plate.
The Hornet Robber-fly, represented on page [731], is one of the most conspicuous of the British species. Among other places, it may be seen flying over the short grass at the top of the cliffs between Brighton and Rottingdean. They are very predaceous, and are probably rather beneficial than otherwise, by contributing to keep down injurious insects. But in North America there is a species called the Bee-killer, which is an extremely destructive insect, taking up its station in front of a hive, and killing large numbers of bees as they fly backwards and forwards from the hive.