Fig. 143.—Scenopinus Fenestralis (Mag.)
Family 28, Lonchopteridæ.—The species of Lonchopteridæ are small yellowish-brown or greenish flies with lanceolate wings. They frequent the banks of shady streams, and are often found resting on wet stones.
Family 29, Syrphidæ.—The majority of flies belonging to this family are of a moderate size, and possessed of brilliant colours. With the exception of the enormous family Muscidæ, they are one of the largest families of the Diptera.
Fig. 144.—Syrphus Ribesii (Mag.)
Most of the species may be recognised at once by their peculiar mode of flight, for they hover motionless in the air, and if alarmed dart off with a rapid motion which the eye cannot follow.
Milesia Crabroniformis is a very large species common in the south of Europe.
About thirty species are found in the British Isles. Of these Syrphus pyrastri is perhaps the best-known example. It is a very wasp-like creature, and is, indeed, mistaken by many people for a wasp. It is a very useful insect, feeding largely on aphides and plant lice, and should therefore be encouraged by every horticulturist.
Family 30, Conopidæ.—The larvæ of most of these insects are parasitic on Orthoptera and Hymenoptera. Many species have a resemblance to wasps in appearance, being striped with yellow and black. The typical genus, Conops, are slender flies measuring half an inch in length.
Family 31, Pipunculidæ.—These are black or brown insects. The head is large and round, generally broader than the thorax. The larvæ are mostly parasitic on other insects. The flies may often be seen in great swarms in shady places in the vicinity of hedges, in lanes, etc.