THE AUSTRALIAN CATTLE TICK. 119 
Taste XLI.—IJncubation and larval longevity of Margaropus annulatus australis. 
IN THE LABORATORY. 
ae Temperature during incubation. 
Ward _ |Minimum 
ae Hatching} incuba- see lar yee Larval 
np began. tion ead. ongevity. Nae y r 
posited. period. Maximum. | Minimum. dae oe Beats 
1908. 1908. | Days. Days. °F. oF, oF. oR 
May 13] June 5 ee acter ee eee eee 88.5 65. 0 77.76 834. 25 
May 14] June 6 DE ah fetela oe is Io gee | sie wiereaoe 88.5 65.0 78.14 843. 50 
May 16] June 8 PEE bee cam oe eee ee 90. 0 68.0 79. 09 866. 25 
OUT OF DOORS. 
May 5] June 6 33 | August 27 82 91.0 43.0 75.31 1, 066.1 
May 6] June 8 34 | August 15 68 93. 0 43.0 76. 04 1,123.2 
May 7] June 9 34 | August 19 71 93.0 43.0 76. 69 1,145.5 
May 8| June 8 32 | August 14 67 93.0 43.0 77.16 1,093.0 
May 11] June 10 31 | August 7 58 93.0 60.5 77.93 1,082.8 
May 13] June 8 27 | August 24 77 93.0 60.5 77.87 941.6 
Three lots of eggs, deposited May 13, 14, and 16, respectively, 
which were kept in the laboratory at a mean temperature of 77.8° F., 
hatched in 24 days, a total effective temperature of 834° F. being re- 
quired for their incubation. Eggs which were deposited by ticks in 
tubes out of doors from May 5 to May 13 commenced to hatch in from 
27 to 34 days. Rohr states that at a mean temperature of 30° C. 
(86° F.) eggs hatched in 19 to 23 days and at 35°C. (95° F.) in from 
15 to 18 days. In this case the total effective temperature would be 
lowered somewhat. Lahille reports an instance in which eggs 
hatched in 20 days but does not give temperature records. He 
states that in one instance eggs deposited on April 30 passed the cold 
months and hatched September 6, or 129 days later. 
The larva (Tables XLI-XLIV).—Our observations on the lon- 
gevity of the larve are based upon the progeny of 6 ticks which 
dropped from a host on April 30, 1908, and which were at once 
placed in tubes on sand out of doors. The eggs from these ticks, 
which commenced depositing from May 5 to 13, were left with the 
ticks and commenced to hatch from June 6 to 10. The larve in the 
several tubes were all found to have died between August 7 and 24, 
or a maximum period of 82 days from the date the larvee commenced 
to hatch. Thus it appears that at Dallas the progeny of ticks which 
dropped April 30 were all dead on August 24, or in a period of 116 
days after the females dropped. 
The larval molt occurs as soon as the sixth day after attachment, 
the last observed to molt having done so on the ninth day. Pound 
states that the molt takes place on the seventh day, Lahille reports 
it to occur from the seventh to the ninth day, while Rohr found 
7 or 8 days to be required. 
