STRUCTURE, DEVELOPMENT, AND P.IONOMTCS OE HOUSE-FLY. 359 
rabbits upon wbicli to rear the larvse of C. ery throcephala, 
I found the broken leg of alive rabbit, which had been caught 
in a spring trap set the previous evening, a living mass of 
small larvae, which were devouring the animal while it was 
still alive. An enormous number of eggs are laid by a single 
insect; Portchinski (' Osten. Sacken,’ 1887) found from 450 
to 600 eggs, though I have not found so many. With an 
average mean temperature of 23° C. (73‘5° F.) and using fresh 
rabbits as food for the larvae, the following were the shortest 
times in which I reared C. ery throcephala. The eggs 
hatched from ten to twenty hours after deposition. The larv^ 
underwent the first ecdysis eighteen to twenty-four hours after 
hatching ; the second moult took place twenty-four hours later, 
and the third larval stage lasted six days, the whole larva life 
being passed in seven and a half to eight days. Foui’teen days 
were spent in the pupal state ; thus the development was com- 
plete in twenty-two to twenty-three day’s. I have no doubt 
that this time could be shortened by’ the presence of a very 
plentiful supply of food, as an enormous amount, comparatively, 
is consumed. 
The full-grown larva may measure as much as 18 mm. in 
length. The posterior extremity is suiTOunded by^ six pairs 
of tubercles arrauged as shown in the figure (fig. 12) ; there 
is also a pair of anal tubercles. The anterior spiracular 
(fig. 11) processes are nine-lobed. The posterior spiracles 
(fig. 10) are circular in shape and contain three slit-like 
apertures. In the second larval instar (fig. 9) there are only 
two slits in each of the posterior spiracles, and in the first 
larval instar (tig. 8) each of the posterior spiracles consists of 
a pair of small slit-like orifices. Howard (1900) found the fly 
on fresh human faeces, and Riley records it as destroying the 
Rocky Mountain locust. 
C. ery throcephala is an outdoor fly, but frequently enters 
houses in search of material upon which to deposit its eggs 
and also for shelter. From its habit of frequenting faeces, 
which may be observed in this country especially in-insanitary 
court-yards, and such food as meat and fruit, it is not improb- 
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