53 



CHAPTER III. 

 SYSTEMATIC POSITION OF THE GENUS. 



The object of the present treatise being essentially practical, it 

 would be out of place to enter at length into questions of classi- 

 fication ; but enough must be stated to enable the reader to 

 understand what are the nearest allies of the Tsetse-flies among 

 existing insects. Suffice it then to say at once that the genus 

 Glossina belongs to the calyptrate division of the Family MusciDjE 

 (MusCARiA ScHizoMETOPA, of Brauer and von Bergenstamm) of 

 the Order Diptera, or Two-winged Flies. Diptera may be 

 characterised shortly as insects with only one pair of wings, a 

 thorax fused into a single mass, and mouth-parts adapted for 

 piercing and sucking, or for suction alone. The metamorphosis 

 is complete ; the larvae are totally different in appearance from 

 the perfect insects, and, though varying greatly in outward form, 

 ai'e usually footless grubs ; those of the Muscidse are generally 

 known as maggots. The pupa either shows the appendages of 

 the perfect insect, although these are enclosed in a sheath and 

 adherent to the body, or else it is entirely concealed within the 

 hardened and contracted larval integument, which forms a pro- 

 tecting case. Diptera have been divided by Professor Brauer 

 into two great groups, termed Orthorrhapha and Cyclorrhapha, 

 according to the manner in which the pupa-case splits to admit 

 of the escape of the perfect insect. In the Diptera Orthor- 

 rhapha, which include the less specialised families, such as the 

 Cecidomyidse (Gall-Midges), Mycetophilidte (Fungus- Midges), 

 Culicidse (Gnats or Mosquitoes), Tipulidae (Daddy Long-Legs), 

 Tabanidse (Horse-flies), Asilidse (Robber-flies), etc., the pupa 

 case splits longitudinally down the median dorsal line. In the 

 Diptera Cyclorrhapha, on the other hand, which comprise the 

 most highly specialised families, such as the Syrphidse (Hover- 

 flies), CEstridse (Bot- and Warble-flies), and Muscidte (sensu laiiorc 

 — House-flies, Tsetse-flics, Blue- and Green-bottlc-flics, Flcbh- 



