A Consideration of the Insect Population Associated 
WITH Cow Dung at Crawley^ W.A. 
235 
F. 10. BORBORIDAE. 
Malloch (1925B) mmtions the occurrence of larvae and adults of this 
cosmopolitan family on manure and carrion in New South Wales. Two 
species of Leptocera frequent carrion at Canberra (Fuller, 1934). In America, 
Howard (1912) reared Limosina (= Leptocera) and Sphaerocera from cow 
dung and human faeces. In India, Borhorus is often infected with a herpe- 
tomonas as is Sphaerocera in France (Patton & Cragg, 1913). Thomsen & 
Hammer (1936) bred Borborids in cow, calf, pig, and horse dung in Denmark. 
They were present in large numbers on pig, sheep, and cow dung at Katanning 
in August, 1941. At Crawley they are associated with carrion, rotting grass, 
cow, and horse dung. 
Most of the small black flies around cow dung at Crawley are Borborids, 
species of Leptocera with a few others belonging to other unidentified Acalyp- 
trate families. The largest species of Leptocera has actually been reared from 
cow dung, though it is the least common in the field. The habits of the preg- 
nant females of the smaller species leave little doubt that they also breed in 
this medium. 
The Borborids are abimdant on cow dung from May to October, with a 
diminution in the complementary period. They rapidly appear on the fresh 
dung. Unlike the Sepsids they can be found actually underneath the dung 
pad. The adults feed on the fresh dung, the pregnant females becoming 
remarkably distended. No information on the immature stages has been 
gleaned at Crawley. 
F. 11. DROSOPHILIDAE. 
Though the usual association of Drosophilids is with fermentable materials, 
some breed in cow dung. They are not common at Crawley in the field, 
being most numerous in July, August, and September, during which period 
their larvae may be found in second and third stage dungs. The Drosophilids 
found on cow dung at Crawley and cow and pig dung at Katanning trace to 
the genus Cladochaeta in Curran’s Key to the North American Genera. 
The larvae are coprophagous and similar in habits to those of Sepsids. 
Pupation occurs in the drier parts of the dung, the pupal period lasting about 
three weeks. 
F. 12. OTITIDAE. 
Only two of the species of this family frequenting cow dung at Crawley, 
Pogonortalis barbifera Macq. and Chrysomyza aenea, Fab., have been identified. 
P. barbifera resembles the Sepsids in the fanning movements of the wings. 
That C. aenea breeds in cow dung on occasion was shown by examination of a 
sample of fourth stage cow dung from Armadale in March, 1941. This dung 
had fermented to the extent that steam rose off it and it felt warm to the 
touch, both unusual conditions. It contained a large number of puparia and 
nearly mature larvae of C. aenea., pupae of Cercyon haemorrhoidalis, one of 
Leptacinus socius, three larvae of Saprinus sp., and a pupa of Musca domestica. 
Specimens in the collection of the Department of Agriculture, Perth, reared 
from larvae taken in silage waste at Boyanup appear to belong to (7. aenea. 
The larvae perform peculiar skipping evolutions when disturbed. The 
body is flexed ventrally to enable the mouth hooks (PI. 1, Fig. 11) to grasp 
the terminal part of the body, probably the raised area roimd the anus. 
Then the longitudinal body muscles are strongly contracted. The mouth 
hooks suddenly release their hold, producing sufficient force to flip the 
