GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 31 
and are swallowed. One author believes that a horse in eating will 
rub the jaws upon the manger, which hatches the eggs, and that they 
are taken into the mouth with the food. The fact that some eggs are 
deposited upon the fore legs and portions accessible to the mouth 
indicates that the ingress of larvee may be similar to that of G. intes- 
tinalis. 
Longevity in this species seems to be increased over that of 
G. haemorrhoidalis, as one reared adult kept under conditions similar 
to those of the nose fly lived for 12 days. 
LARVA AND PUPA STAGES. 
Coincidentally with the appearance of G. haemorrhoidalis at the 
anus of horses, the larvee of G. nasalis occasionally may be observed 
to pass normally from horses and be found in their droppings. This 
normally occurs when larve become fully developed and is often 
attributed by farmers to “a destructive effect of grass upon the bots.” 
These larve seldom migrate a great distance, and apparently only 
burrow under the droppings for protection. Larve which dropped 
normally pupated in from 14 to 2 days, though the prepupal periods 
in some cases in which larve were removed in autopsies and cited in 
Table VII extended for 7 days. It was observed that the short pupal 
periods were preceded by long prepupal ones, and that larve pupat- 
ing within 2 days after dropping emerged in from 42 to 45 days. 
At Victoria, Tex., Mr. J. D. Mitchell collected a larva under manure, 
which pupated October 6, 1914, and emerged 20 days later. To 
rear larve collected in autopsies is a difficult task, even though they 
are well developed and appear normal, but during the late summer 
a small percentage may be reared if they are collected from horses 
immediately after death. The larve removed from dead animals 
are capable of remaining alive and active for some time, some having 
been kept as long as 25 days. Some larve have been observed to 
live submerged in water for 12 days. 
Taste VII.—Pupal periods of Gastrophilus nasalis, Aberdeen, S. Dak., 1915-16. 
o/s 3) 
@ 2} 4 | Number 5 sp | Temperatures. 
P S| 5,. | emerged.) a-5 
Larvie 3S Blea So 
col- Location. i Breeding environ- | = | C8 | 3 Gs S) Wir ; 
lected. 2 ment. er ey |e | Diet ete bealiel ae 
: ple |2| # |S lasicel 2 
3} 3S 3 oa =| 2) 
Z Paes plese ie, ee | 
1915. Days. | Days.| °F.) °F.) °F. 
June 4 Fresh dropping.....--. 1 | With horse manure.| 1 EO el Ale See tenors 88 | 35 | 65.30 
1916. 
May 29 |..... Glan aneeetoee 2 | Clean tinbox; moist | 2 | 44-45 | 1 lees | 94 | 42 | 67.93 
sand. | 
June 12| Dropped from treat-| 4 |..... MOS osc eee 1 eri ata eae 7 | 94 | 42 1168.98 
ment. | 
Dtlve LOM eDimod ent.) 2-25 -- a. = 19 | Dry paperintin box.} 3 | 25-33 | 2 | 3-15 | 98 | 41 | 72.77 
AT See STOMACHS. ss. Sues 18) | {Moist sands: 53 3 ACh linpl ai eee | 3-8 | 98 | 28 | 60. 26 
Hs eDwodentimls-—---25---- Spies eee Gosen seco tee | 8 56 | 1 1 11 | 95 | 28 | 59.97 
1 Horse treated with carbon disulphid. 
