GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 25 
possessed a normal longevity as compared with others in rearing 
experiments. 
The above percentage of mortality is based upon those experiments 
in which the fungus occurred. As there seems to be no reason for 
attributing the fungus to soil or media it is well to base this per- 
centage upon all experiments in tin boxes and where pupe were in 
close proximity. In Tables II and VI, 630 larvee produced 578 pup. 
Of these 247, or approximately 43 per cent, developed a fungus. Of 
the ones kept under observation 57 per cent emerged, so that only 43 
per cent of the infected pupe were rendered inviable; 43 per cent 
of 43 per cent would approximate 18.5 per cent, or the percentage of 
loss in rearing experiments where numbers were kept in close prox- 
imity, which probably allowed the infection to spread over indi- 
vidual lots. 
In Table ITT it is shown that no infected pupe were found, and 
should a fungus develop in such conditions the single location of 
pupe would prevent its spreading. This fungus has never been ob- 
served upon normal G@. intestinalis or G. nasalis, though with dead 
jarve of any Gastrophilus a long growth of fungus quite different 
from that met upon living G. haemorrhoidalis pup is frequently 
found. 
PREDATORS AND PARASITES. 
The dropping of larve under varying conditions and in locations 
where they do not pupate in close proximity renders the situation 
such that very little could be expected of predators and parasites in 
control. In rearing experiments some field mice devoured pupz 
on grass sod, but even though they feed upon these in nature it 
is not lkely that a great many are devoured. Chickens probably do 
not feed upon many larve when they drop, though a single hen has 
been known to devour about 40 dead G. intestinalis removed from a 
horse by a carbon disulphid treatment, and without any noticeable ill 
effects upon the chicken. 
Desiring to know if the widely distributed Nasonia brevicornis, 
which parasitizes various species of dipterous pups, could be reared 
upon G. haemorrhoidalis pupe, repeated efforts were made, but with- 
out success. The indications are that the flycatchers feed very little 
upon Gastrophilus adults. On account of the danger in shooting 
such birds in pastures very few examinations of stomachs have been 
made. 
LIFE-HISTORY NOTES. 
ADULT LONGEVITY. 
The life of adults appeared so short at the beginning of expevi- 
ments that it was attributed to abnormal conditions, but various cages 
and environments did not materially increase the periods. <A total of 
11216°—18—Bull. 597-4 
