57 



Family 

 MUSCID/E. 



The three British blood-sucking species belonging to this Fam'iy 

 are all nearly allied to the Common House-fly {Miisca domestica, Linn.), 

 but derive an even greater interest from their close relationship to the 

 African Tsetse-flies (Genus Glossina), one species of which, Glossiiia 

 palpalis, Rob.-Desv., is now widely known as the disseminator of the 

 parasite which is the cause of the dread disease called sleeping 

 sickness. In the Muscida;, which, in the widest sense of the term are 

 perhaps the largest of all the families of Diptera, the blood-sucking 

 habit is highly exceptional and is confined to a very few genera 

 and species, all of which in appearance present a general resemblance 

 to the Common House-fly. In cases in which the blood-sucking habit 

 occurs, it appears to be common to both sexes. 



Blood-sucking Muscidae, with the exception op the Tsctsc-Jlics, 

 breed in dung, depositing eggs from which are developed white 

 maggots of the type of those of the Common Blow-fly {Calliphora 

 eiythrocephala, Mg.). According to Riley and Howard, Lyperosia 

 irritaiis, Linn. {Hceinatobia scrntta, Rob.-Desv.), (Plate 30, fig. 2), 

 oviposits on fresh cow-dung, and its eggs are irregularly oval in shape, 

 flattened on one side, and from r25 to 1-37 mm. in length, by 0'34 to 

 0"4i mm. in width. The newly-hatched larvae descend into the dung, 

 and eventually when full-grown attain a length of 7 mm. Pupation 

 takes place in the ground beneath, at a depth of from half to three- 

 quarters of an inch. The pujiarium is of the normal Muscid type, 

 dark-brown in colour, barrel-shaped, and from 4 to 4'5 mm. in length 

 by 2 to 2"5 mm. in width. Stoiiio.xys calcitnms, Linn., breeds 



in horse-droppings, and its larva; are very similar to those of the 

 Common House-fly, which also breeds in horse-dung. 



