22 BULLETIN 597, U. S. DEPARTMENT OF AGRICULTURE. 
Upon hard soil the larve are seldom observed to move more than 
a foot, and this sometimes requires 15 minutes. The tendency seems 
to be confined almost wholly to burrowing, and it is only when 
dropped on unsuitable places that they migrate. When exposed 
upon hard, barren soil to the heat of the sun during the summer it 
seems certain that only a few find protection and eventually produce 
adults. Certainly those not finding suitable protection from the sun’s 
heat die within a short time. On black loam at a mean temperature 
of 122.9° F., 8 to 12 minute exposures caused 100 per cent mortality. 
Yet some larvee seem to withstand even higher temperatures, for 
adults were produced after having been exposed from 5 to 17 minutes 
at a mean of 129° F. Pupe, being unable to accommodate themselves 
by moving for protection, seem to be very susceptible to heat. Ex- 
posures of from 30 to 137 minutes at 116.6° F. were sufficient to 
render them inviable. 
The heat generated in a manure pile produced greater mortality 
upon larvee than ordinarily would be expected. Larvee buried with- 
out protection at a mean temperature of 151.7° F. were dead within 
15 minutes, having become soft and white. 
EFFECT OF SUBMERGENCE ON LARVA AND PUPZ. 
Although, as shown in Table III, excess moisture seems to have 
had a destructive effect upon pupe, the effect of submergence upon 
larvee is not so great. Larvee submerged 51 to 74 hours pupated and 
produced adults. (See Table V.) Larve submerged for 80 hours 
pupated, but failed to emerge when kept under favorable breeding 
conditions. While it is difficult to submerge pupe, as they float and 
expose a portion of the posterior spiracles, three normal ones kept in 
water for 5 days failed to emerge. In view of the results in Table 
II, it is apparent that great mortality occurs among pupe during 
wet seasons, 
TaBLE V.—Effect of submergence on larve and pupe of Gastrophilus haemor- 
rhoidalis at Aberdeen, S. Dak., 1915-16. 
| Larval Temperature after 
lon- period of 
| gevity, submergence. 
Date | | Num- | 4 quits | include | Collee- 
sub- Stage. Pan Eenlod d Dene emerged,| ing fon to 
merged. | | a SUN OMT ANC ea “| (male.) | period serge! 
; Soe | 
| esp Max. Min. Mean. 
gence. 
1915. OU OB altered th CIR 
July 5..| Larve... 6 85 | 41 63. 93 
Til 1452\ doeeee 3 85 41 64. 21 
DOs) COs ses 3 85} 41 62. 95 
uly, 245°| doves 5 s0| 40] 58.14 
July 2..| Pup... 3 s2| 40) 59.40 
1916. | 
June 7..) Larve.. 9 76 43 64. 83 
Done doses 5 j aeecO 43 64. 83 
July 12.. Goezeee BW |e eeG ays a's Neca Fists wc ayes esl oie ee chill easeise Bie | 96 64 76. 50 
DO-s4]| COS Sse || QO IMOWS-ocacososase Gl sreraise Be coe | 96] 64 75. 90 
Dowel dose BaarG Ayes suecce Get tas eee eee (jal Sree | 96 | 64| 76.50 
| 
