Family 32, Platypezidæ.—This family contains many beautiful flies. Great numbers of them are marked with orange and silver and black. The larvæ inhabit fungi.
Fig. 145.—Eristalis Simili (Mag.)
Family 33, Æstridæ.—The Bot Flies are well known on account of the annoyance they cause to cattle. They lay their eggs upon the hides of the animals, and the larvæ, when hatched, make their way under the skin, and there take up their abode, living on the juices of their unfortunate host. It is estimated that the loss occasioned by these troublesome pests amounts to millions of pounds in the British Isles alone. The best-known species is probably Æstrus bovis, which infests the ox. The cattle are so well aware of the danger attending the presence of this insect, that as soon as it appears near them, the whole herd exhibits the most unmistakable signs of terror, rushing about their pasture with their tails in the air, and in case of need taking refuge in water, where the fly will not follow them. Miss E. A. Ormerod has recently paid much attention to the economy of this insect, with the view to finding some remedy for its attacks.
Fig. 146.—Nemestrina Longirostris (Mag.)
Family 34, Muscidæ.—The Muscidæ is the most numerous family, of the Diptera and it includes many familiar insects. It is divided into two sections, containing thirteen sub-families. The first section, Calypteræ, contains five sub-families. The Tachininæ are parasitic in the larval stage on Lepidoptera. The largest of the Muscidæ found in Europe is Echinomyria grossa, which measures about three-quarters of an inch in length.
Fig. 147.—Volucella Zonaria.
