G. J. Snowball. 
F. 9. SEPSIDAE. 
Tliese are characteristic excrement insects with a world-wide distribution. 
Sepsis viotacea, Meigen. breeds almost exclusively in excrement, including 
that of man (Howard, 1912), There are 30 species of Sepsidae in Great Britain 
(Imms, 1938). In Denmark, numbers of Sepsis sp. emerged from cow, horse, 
and pig dung (Thomsen & Hammer, 1936). Sepsids are common in the 
tropics on dung of all kinds (Patton & Cragg, 1913). In Australia “the 
known species of the family occur in the adult stage on garbage, carrion, or 
vegetation, some being very abundant on flowers. The larvae feed in manure 
and carrion ” (Malloch, 1925A). 
At Crawley, Sepsids are the most characteristic flies on cow dung. Two 
species are present, viz., Australosepsis fulvescens. Mall., which appears to 
contain only males, and its black variety atratula. Mall., of which both males 
and females are known, and Sepsis pleheia, de Meij. Both species breed in 
cow dung in the field. 
A. fulvescejis is most numerous from November to May, and S. plebeia 
during most of the year excej^t January and February. The latter species 
was collected at Katanning in August, 1941. Both are members of the 
carrion association at Canberra. A single specimen of S. hirsuta, de Meij., 
was bred from cow dung at Dog Swamp, Tuart Hill, W.A., in January, 1942. 
The vSepsids appear on the fresh dung and remain until after the super- 
ficial skin has become a firm crust, spending the time in feeding and oviposi- 
tion. While parading on the dung they generally pair ofl and indulge in 
remarkable antics. Each female carries a male, which applies its labella to 
her cervical membrane and engages its legs on her prothorax. They remain 
for hours thus, keeping up a ceaseless movement of legs and wings, yet tlie 
time of actual sexual contact is short. 
Oviposition has been observed only in Sepsis plebeia. The female, still 
carrying the male, partly extrudes the egg several times before depositing 
it with a sudden thrust of the abdomen. Usually buried in the dung, the 
egg is occasionally merely dropped on the surface of the cake. Sepsids are 
frecpiently seen ovipositing in dung in which eggs of large Muscids have al- 
ready hatched. This is probably due to the Sepsids remaining for a 
longer time on the dung, because it is their main food, than do the Muscids, 
in the diet of wdiich it is only a subsidiary item. 
Only one egg is usutilly laid in a particular spot. Constant returning of 
the female to the same place results in the formation of large clutches of eggs 
just below the surface with the interlacing respiratory processes (PI, 1, 
Fig. 9) forming a white network which is often conspicuous on the surface. 
The eggs hatcli in about 24 hours. 
The larvae (PL 1, Fig. 10) are truly coprophagous, occurring mostly in 
second and third stage dung, occasionally in the first and very rarely in the 
fourth. The length of larval life is apjDroximately 10 days. 
Pupation normally occurs in the dung itself, usually in the peripheral 
layers, sometimes on the lower surface. The pupal period in September, 
1941 (average' temperature, 13 9“ C.) was 23 days. Tlie total life history 
from laying of the egg to emergence of th<^ adult took 33 days in September 
aiid October (average temperature, 16*1° C.), 1941. 
Because they occur in large numbers and not only consume but tunnel 
through the dung, the la,rvae assist greatly in changing its nature. They are 
parasitised at Oawley by an unidentified Alysiui which emerges from the 
puparium. It is not an efficient pai'asite as infested stages are not common. 
