GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. ILT) 
lowish, the larva contracting and assuming the form of a pupa. As 
the puparium becomes more hardened a reddish tinge appears, but 
after a few days it becomes black and retains this color until the 
adult emerges. 
TasLeE II1.—Some environmental effects on metamorphosis of Gastrophilus 
haemorrhoidalis at Aberdeen, S. Dak. 
| 
Temperature, col- Lon- 
lection to emer- | gevi- 
Larvee Agar ‘Num-|Num ty 
ay Pre- | z ‘| Number] of 
collected Environment. pupal | Pupal ber | ber | “adults llarves 
from acl period. lar- | pu- d t 
rectum. pero ve. | pe. |omersed.) no 
Max. | Min. | Mean. | Due 
pat- 
ing. 
1915 Hours.| Days. | oR) 258, \\ 0 B. Days 
June 4] Fresh horse manurein tin box) 27-47 | 39-45 88 | 35] 63.21) 14 14 10 ee 
Tune. 5) 2 Oca Sees Sees eee ere 24-72 | 46-54 88 35 | 64.76 | 33 31 22 4 
Tune Sees ee GOSaE a EE ates 2 ot 384-52 | 37-44 88 35 | 64.93 16 13 8 8 
June 8]..... LO See emcee aca sictesiciee 49 | 38-40 88 35 | 65.67 ra 7 DB Raat 
Hume: 9) Clean tin’ box. 2 -—.2.--:--..2- 35-55 | 36-48 88} 35] 65.02] 12 11 Oh eas 
June 12 Glass jar and fresh horse ma- | | 
TITIROM EP REE ya None os | 58-146 | 33-36 88 40 | 65.73 | 14 14 His boke 
June 15 | Dry hard soil......--.-.-.---- 75-122 | 28-30 85 40 | 62.40 10 10 iiligeaane 
Do...| Moist horse manure...-.------ | 122 | 29-31 85 40 | 62.56 10 8 7 | 15-22 
Doses | Cleamtin’ POx=.- 2-2 s-4-0--- | 120 | 31-32 84 40 | 62.89 7 6 4 15 
June 14 ]..... Ome ee eee aceisa 50-144 | 30-38 84 40 | 64.33 27 25 18 4 16 
June 18'_.... (6 Koo Sa ea spe eae ae ae 27 =} 32-42 84 40 | 63.23 34 30 26 12 
June 17 | Moist manure in tin box..--- | 18-47 | 34-40 84 40 | 62.06 33 33 285 ese 
July 12 Black loam in tin can......-- 23-39 | 34-35 85 40 | 64. 23 8 5 B llasadan 
Atige ie Onverassisod: 5. 22---2-0 52- 19-26 | 58-68 88 | 132 60.59 7 7 Si beeees 
1916. 
Mavae22 Olean tin POX. -- ssc soccce 68 41 94 42 | 62.62 5 4 Que eysieg 
Wen 25) esos 610). aCe Se eran 52-72 | 36-40 94 42 | 62.81 5 4 3 11 
May 30 |...-.- GO See pee ee eects s 141-170 | 34-35 94 42 | 64.79 2 2 1a lteaeee 
May 31 |...-.- (IO) pen et oa cenbeceSonercone leadeusen 35 94 42 | 60.08 1 1 Lil iosees 
June 3 |..... OEP ee eincetenieemsek 42-96 33-34 94 42 | 65.55 11 8 5 5 
June 5] With moist sand...........-.- 75-100 | 32-35 94 42 | 66.69 17 17 NG) We eesbo 
June 10|....- CLO eee e Sa hysee nici | 44 30-32 94 42 | 68.15 28 25 20 4 
June 23 | Clean tin box and moist loam.|......-. 21-24 96 48 | 74.08 46 44 38 5 
1 Minimum, Sept. 21. 
In rearing larve to adults a most convenient and efficient method 
was utilized by placing them in clean tin salve boxes upon moist sand 
in bread pans. Table II gives some results of rearing under such 
conditions, using various media within the tin boxes. The period of 
collections extends from June 4 to August 7, which includes prac- 
tically the entire season during which larve appear at the anus of 
horses in Aberdeen, S. Dak. It will be observed that the prepupal 
stage, the period from removal of larve until pupation, varies from 
18 to 170 hours. This is a much greater range of time than is normal 
and may be attributed to the fact that larvee were removed before the 
critical period of dropping. In some instances under varying con- 
ditions they did not pupate, and, while some larve died within a few 
days, one is recorded as living for 22 days. 
The removal of larve from the rectum prior to their normal ex- 
posure to the air at the margin of the anus has a pronounced effect 
upon rearing. A small percentage have been reared which were fully 
11216°—18—Bull. 5973 
