—— 
THE CATTLE GRUBS OR OX WARBLES 73 
LONGEVITY OF ADULTS 
Owing to the fact that the adults of Hypoderma are very rest- 
less when in captivity and since there seems to be no means of 
keeping records of specimens in nature, the writers’ observations 
on the length of life of the adults may give erroneous ideas. The 
longevity of reared adults of H. lineatwm is shown in Table 10. It 
ranged from 1 to 25 days and averaged somewhat longer for males 
than for females. The markedly greater longevity observed among 
about 50 adults reared in the laboratory during the spring of 1924 
than had been noted previously indicates clearly the probability 
that certain individuals which emerge prior to periods of uniformly 
cool weather may live for a considerable time. The specimens re- 
ferred to were hastened in their emergence by being kept in a 
warmed room. After emergence the adults were transferred to 
lantern-globe cages and kept in an unheated room. The tempera- 
tures given in Table 10 for these records for 1924 were those re- 
corded in a standard weather shelter out of doors, and hence un- 
doubtedly show a much greater range of temperature than was 
actually experienced. There is no question but that in nature the 
flies would seek the sunshine and warmer places which would stimu- 
late activity, and thus we should not expect to find such long periods 
of existence as those referred to above. The writers’ observations 
in the field also bear out this assumption. It seems certain that 
when the weather is warm and the adults are active their lives are 
uniformly very short. 
TABLE 10.—Adult longevity of Hypoderma lineatum at Dallas, Tex. 
Num- Temperature 
um 
Date her ber 1 a ae 
adults of of Record of death ait Remarks 
emerged Petes tes Bey Min. | Max.| AVe!- 
males : age 
1915 1915 Days C10 | ae OT 
FADES V2i fe To | GA prelOw armas 620 ec ue 7 | 48.0 | 83.5 | 67.6 | In cage 1 foot by 1 foot 
by 1 foot, with leaves. 
ATS 19) oe Apic2e:sp Ms 2 a2a2 2 ee 3 | 54.0 | 82.0 | 69.0 In small cage, with 
leaves. 
1916 1916 , 
Mar. 20 1 3 | Mar. 21,2 9; Mar. 22,1 9; 1to 31! 61.5 | 97.9 | 80.2 | In cagel foot by 1 foot 
Mar. 23,1 o. by 1 foot in sun. 
Mar. 22 10 10 | Mar. 23,1 9; Mar. 24,167, 1to 7 | 38.0.| 88.0 | 61.7 | In small and. large 
2 9; Mar. 25, 307, 59; cages and on cow. 
Mar. 27, 29,1 o&; Mar 
28, 26°; Mar. 29, 3c". 
Mar. 27 2 2 pee ee: 2; Mar. 29,27, lto 2] 39.5 | 88.0 | 66.3 Do. 
1918 1918 ; 
Feb. 25 D4il pty Feb. 27,1; Feb. 28,1c_-| 2to 3 | 38.0 | 97.5 | 66.2 | In laboratory. 
Feb. 26 1 5 Fe ae 1 o',3 9; Mar.1, 2to 3 | 38.0 | 87.0 | 58.2 Do. 
Hebi27) | 222.8 Tf lah Ue ts Ue gs 2 eA ei a 2 | 38.5 | 87.0 | 56.2 Do. 
Mar. 11 3 1 | Mar. 14, 2 o', 1 9; Mar. 3to 8 | 33.7 | 90.0 | 60.9 |; In 1-inch tubes (@ de- 
19,16. posited). 
Mar. 13 2 1 | Mar.15,1 9; Mar.19,2c¢'_| 2to 6 33.7] 90.0 | 56.5 | In 1l-inch tubes with 
leaves. 
1921 1921 
Mar. 7 8 1 | Mar.14,2¢; Mar.15,4 4, 7to 9 | 36.0 | 87.0 | 63.4 | In lantern globes with 
19; Mar. 16,2¢. leaves. 
Mar. 8 8 1 | Mar.12,1 9; Mar.13,10; 4to 9 | 36.0 | 87.0 | 64.0 
_ Mar. 15, 16°; Mar. 16, 
4 9; Mar. 17,2. 
Mar. 12 10 8 | Mar. 13,1 o&; Mar.15,1 @; 1to 8} 51.0 | 87.0 | 71.7 | In cage 1 foot by 1 foot 
peat Bo 7 o',8 9; Mar. by 1 foot, with leaves. 
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