it is obvious that the number necessary to do this must be astonishingly great. About 1700 have been named as belonging to this country; and it is probable that they will ultimately be found not to fall short of 2000.
Allusion has been already made to the injuries they commit, in the larva state, both to our domestic animals and to agricultural produce; but the purposes to which they are subservient in the economy of nature, are highly important and beneficial. Many of the smaller birds, as well as some other of the higher animals, depend upon them almost exclusively for food, and they are the most efficient instruments employed by nature in removing both animal and vegetable substances when rendered offensive and unwholesome to other animals by decomposition.
The most successful of the more recent investigators of this order are German and French Entomologists, particularly Meigen, Fallen, Wiedeman, Macquart, and Robineau Desvoidy. The following is Macquart's arrangement, slightly modified, for which we are indebted to Mr. Westwood's useful text-book:[1]
Section I. (Ovipara or Larvipora; Diptera, Leach.)—Head distinct from the thorax; sucker enclosed in a labial canal; claws of the tarsi simple, or with one tooth; the transformation to the pupa state not taking place within the body of the parent.
Division I. (Nemocera.)—Antennæ having six or more distinct joints; palpi with four or five joints.
- ↑ Page 420.
