GASTKOPHILUS HAEMOREHOIDALIS AND OTHER BOTS. 23 



Larvae 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 after 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 larvae, 

 to one of which a particle of horse manure adhered. They were 

 collected from the rectum of perspiring horses, and it appeared that 

 the fungus developed from the manure and spread to the larvae and 

 pupae. The larvse giving promise of fungus development were 

 placed in a clean tin pill box with three well-washed G. haemor- 

 rhoidalis larvse, 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 all the larvse 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 larvse. 

 As this fungus had developed upon larvse collected from perspiring 

 horses, it seemed possible that such larvse 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 larvse kept under normal rearing condi- 

 tions, as given in Table VI, a fungus appeared on the pupa stages 

 which apparently spread to other pupse in the same lot. In some lots 

 pupae 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 pupse it 

 appeared within from 3 to 17 days after collection. 



