184 LIFE HISTORY OF NORTH AMERICAN TICKS. 
TaBLE LXXXII.—Preoviposition, incubation, and longevity of larve of Dermacentor 
occidentalis. 
fg Temperature during incu- 
Mini- bation. 
D i Hes L 1 
Date engorged female | ;,°P°S' | Hatching| Cu aie 
dropped or collected. ODE began. | 22 Ai larvee'dead.: tne Aver- 
gan. tion GO teescal ier) oe Total 
e- ge | effec- 
o d mum.|mum.| daily F 
od. mean. tive. 
1910. 1910. 1910. | Days. 1910. DOYS aelien | oop gis oF, 
SDE 2 EKeolisered) weer Apr. 15 | May 19 35 | Before July 16. 58—| 91} 43 70.16 | 950.6 
BS anceineee esc Apr. 14] May 17 34 | July 16-Aug. 4.}105-124 91 | 43 70.72 | 942.48 
Apr. ei (collected)... .- Apr. 21 | May 25 35 | July 18-Aug.4.} 5471 91 | 43 71. 43 |1, 012.0 
Apr. 12 (collected)....- Apr. 26| May 26 | eta GO se ae 53-70 O91 | 52.5) 73.19 | 935.75 
Apr. 13 (dropped)....- Apr. 27} May 28 32 | Before July 18. 51—| 911] 58.5] 74.23] 999.50 
May 3 (collected).....- May 10] June 16 38 | July 18-Aug.4.} 32-49] 100 | 59 77.92 |1, 326.9 
DOS: teach eeenes May 13] June 7 26) leases do .2Sesesce 41-58 | 100 | 59 77.07 | 885.75 
May 9 (dropped)....... May 16] June 10 26} Aug. 4-12..... 55-63 | 100 | 60 79.28 | 943.25 
May 11 (collected).....} May 20] June 12 P.O (ee See GO ae 53-61 | 100} 60 80.09 | 890.25 
May 13 (collected)..... May 23] June 14 23 | July 18-Aug.4.} 4461] 100 | 60 80.25 | 856.75 
May 15 (collected)..... =| es, 24 | June 16 DAW Eos .2 dogssces-8 - 32-49} 100 60 80.71 | 905.25 
May 29 (dropped).. June 4] June 24 7 eee dOessccacse 24-41 97 | 66 83.1 842 
June 20 (dropped)... Lscene June 24 |.July 14 21 | Aug. 12-20....| 29-37 98 | 73.5 | 85.7 896. 75 
Noy. 15 (collected)... .. Dec. 12'| Dec. 27°) 116 | Mar.18) 1911... 81s rel cemeees 90" Hue aee 
(about) 
WOM ser woes eee e Dec. 16} Dec. 31} 116 | Mar. 14.1911... Laid ie etre || Seeate Ue eeces 2c 
(about) 
1 Kept in incubator during incubation. 
The larva (Tables LXXXII—-LXXXV).— The longevity of the 
larvee of this species is somewhat shorter than that of most of the 
other species of the genus Dermacentor. The greatest longevity accu- 
rately recorded occurred in the case of a lot of larvee which hatched 
May 17 and on subsequent days. The longest-lived larve of this 
lot died between 105 and 124 days after hatching began. A large 
number of records of larval longevity were made on the progeny of 
individual ticks. In the majority of the lots all larvee were dead 
within two months after the hatching of the eggs began. All of 
the records on longevity were made upon larve kept in tubes with 
cotton stoppers, on moist sand in the laboratory. 
Engorgement may be completed as soon as 3 days after attach- 
ment to a host. The greatest number of engorged larve dropped 
from the host on the third, fourth, and fifth days after attachment. 
A single larva was found to have dropped the second day, but since 
this specimen was not fully engorged it is quite probable that it was 
rubbed off by the host. This statement probably applies to all 
larvee which were found to have dropped before becoming fully 
engorged. The longest period required for engorgement was 7 days. 
In most instances larve were found to attach within a few hours 
after being applied to a host. In our experiments only a small 
percentage of the number of larve put on a host ever reached 
engorgement. 
