GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 23 
Larvee have been observed to remain alive during submergence for 
from 14 to 20 days; those submerged 6 and 7 days live for some few 
days aiter removal. 
NATURAL CONTROL. 
FUNGUS DEVELOPMENT. 
Under conditions the same as those upon which adults were reared 
in Table II apparently two species of fungi developed upon living 
material. The first mentioned in Table VI occurred upon three larve, 
to one of which a particle of horse manure adhered. They were 
collected from the rectum oi perspiring horses, and it appeared that 
the fungus developed from the manure and spread to the larve and 
pupe. The larve giving promise of fungus development were 
placed in a clean tin pill box with three well-washed G. Aaemor- 
rhoidalis larve, which had been exposed to the air at the anus of a 
horse for about 24 hours preceding the washing. The fungus de- 
veloped upon ail the larve and death ensued. This fungus was 
determined by Mrs. Flora W. Patterson, Mycologist of the Bureau 
of Plant Industry, as Sporotrichum minutum. This, with one ex- 
ception, was the only lot in which fungi appeared on living larve. 
As this fungus had developed upon larve collected from perspiring 
horses, if seemed possible that such larve as were not washed might 
have developed a superficial growth. Later. collections were made 
from work animals which were perspiring during the time of collec- 
tion, and they were kept under similar conditions, but no fungus ap- 
peared. In collections of larve kept under normal rearing condi- 
tions, as given in Table VI, a fungus appeared on the pupa stages 
which apparently spread to other pupe in the same lot. In some lots 
pup remained without becoming infected, but in others it even 
developed upon various parts of the tin boxes. The collections and 
rearing methods used in these experiments were not unlike those in 
which no fungus appeared, as new, clean, but unsterilized tin boxes 
were used in each breeding experiment, and sterilized forceps were 
used in handling. The soil or medium was different in the various 
boxes, but since these various conditions were also present in lots 
which developed no fungi, there appears to be no reason for attrib- 
uting it to the type of soil or to the medium. Upon the pupz it 
appeared within from 3 to 17 days after collection. 
