78 
Transactions of the Royal Society of South Africa. 
EMPUSA, Cohn. 
Cystidia and rhizoids absent. 
Conidiophores simple or branched. 
Emimsa muscae, Cohn. (Plate II, figs. 1-4.) 
Conidia bell-shaped, with a broad, subtruncate base, 18-20 x 25-30 fx. 
containing usually a single large oil-globule, and surrounded after discharge 
by a mass of protoplasm. Conidiophores simple, club-shaped, emerging in 
white rings between the segments of the abdomen of the host. Secondary 
conidia spherical, formed by direct budding from the primary conidia. Host 
attached to substratum by proboscis. 
Hosts. — Muscid flies. 
Habitat. — Cosmopolitan. 
This is perhaps the commonest and most familiar of all the Entomo- 
phtJioraceae. It was first noticed at Cedara on a large species of Anthomyid 
fly out-of-doors on August 17, 1919. A number of these flies were found 
dead in the garden on this date, fixed to foliage by their proboscis. The 
first house-fly killed by this fungus was found in the house on a window- 
pane on October 18. It was found to be common on house-flies at Umfolozi 
in Zululand in November. The disease was prevalent at Cedara until the 
first week in January, when it suddenly disappeared, no specimens dying of 
the disease being found after the 7th of this month, although house-flies 
were abundant and the weather damp and warm. 
By collecting all the dead house-flies in the house each day and keeping 
a careful watch it was found that all the victims of the disease died in the 
evening, somewhere between 6 and 8 p.m. The following notes are typical 
of several records made : 
" Specimen 1, 6.55 p.m. — Adhering to window-pane by its proboscis. 
When removed could still move its antennae and proboscis. 
" 7.5 p.m. — Slight twitchings of antennae only signs of life. 
7.10 p.m. — Quite dead. 
" 7.30 p.m. — Intersegmental membranes of the abdomen distended and 
gleaming white. 
" 9.30 p.m. — Protrusion of conidiophores well marked. 
" 10.15 p.m. — Large numbers of conidia have been thrown off. 
" Specimen 2, 6.55 p.m. — This individual could buzz its wings and walk 
quite freely, but could not fly when found. 
" 7.10 p.m. — Can walk feebly. 
" 7.20 p.m. — Proboscis and antennae still retain power of movement. 
" 7.30 p.m.— Dead. 
" 10.15 p.m. — Conidiophores prominent. 
" 11 p.m. — A few conidia have been thrown off. 
