(120) 



ST11UCTUBK, DEVELOPMENT, AND BIONOMICS OF HOUSE-FLY. 361 



is difficult to say whether it is parasitic or whether it feeds on 

 the rotting pupae only ; many observers are inclined to take 

 the last view. The larva may reach a length of 11 mm. It 

 is creamy-white in colour ; the anterior spiracular processes 

 are five-lobed and are like hands from which the fingers have 

 been amputated at the first joint. The posterior spiracles 

 are rounded and enclose three triangular-shaped areas, each 

 containing a slit-like aperture. I have not been able to study 

 the complete life-history, but Taschenberg (1. c.) states that it 

 occupies five or six weeks. 



(9) Lucilia Caesar L. 



Although it is not a house-fly, this common fly occasionally 

 occurs in houses, especially those in the country, and it is often 

 called a "blue-bottle." It is smaller than C. erythrocephala 

 and is more brilliant in colouring, being of a burnished gold, 

 sometimes bluish, and also of a shining green colour. 



It frequents the excrement of man and other animals in 

 which it is able to breed. Howard (1. c.) reared it from human 

 excrement. It also breeds in carrion, but the chief breeding- 

 place in which I have found it in this country is on the backs 

 of sheep. It. is one of the destructive species of" maggots" 

 of sheep. The larvae are very similar to those of C. erythro- 

 cephala in fact, Portchiuski considered them indistinguish- 

 able from the larvae of the latter except in size. The full- 

 grown larva measures 10-11 mm. in length. The larval life 

 lasts about fourteen days, and the pupal stage a similar length 

 of time, but I have reason to believe that under very favour- 

 able conditions development may take place in a much 

 shorter time. 



(10) Psychoda spp. 



There may be found frequently on window-panes small, 

 grey, moth-like flies belonging to the family Psychodidae. 

 The wings of these small flies are large and broad in propor- 

 tion to the size of the body, and are densely covered with 

 hair ; when the insect is at rest they slope in a roof-like 



