STRUCTUKK, DEVELOPMENT, AND BIONOMICS OP 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 ai’e 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 Cmsar 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 ai’e very similar to those of C. erythro- 
cephala — in fact, Portchinski 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, inoth-like flies belonging to the family Psychodidse. 
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 
