106 LIFE HISTORY OF NORTH AMERICAN TICKS, 
The minimum incubation period recorded was 19 days. This record 
was made on eggs deposited on August 21 and kept at a mean tem- 
perature of 83.5° F. An effective temperature of 774° F. appears to 
be required for incubation. Christophers states that eggs hatch in 
3 or 4 weeks. 
TaBLeE XX XII.—Jncubation and larval longevity of Rhipicephalus sanguineus. 
IN THE LABORATORY. 
Temperature during incu- 
bation. 
. Minimum 
Eggs deposited.| 42thing | incubation | All larvee dead. | Larval lon- 
gan. aa gevity. Aver- 
Peewee Maxi-| Mini-| age Total 
mum.|mum.| daily “« oa 
mean es 
Days. Days i 5) a? OPE Wa ede 
Mar. 31, 1908..... May 10,1908 AVS We ade Sum aseie oe sec Meee ee ee 85.0 | 47.0 | 69.00 |1, 066, 37 
Apr. 18, 1908... - May 26, 1908 39 July 7, 1908. 42 | 87.0} 47.0 | 72.18 |1, 138.25 
Apr. 20, 1908....| May 27,1908 5 el BE cssaoccorcccda) Eeabtecmcmes 87.0] 47.0 | 72.38 |1, 082. 25 
Apr. 22, 1908....| May 26, 1908 35. hilt: cance ee re A lakes eae oe 87.0} 47.0] 72.05 | 986.25 
July 7, 1908....-.- July 27,1908 21 Oct 7,01908eee-e 72 | $5.0} 74.0] 83.99} 860.50 
July 29, 1908....- Aug. 17, 1908 20 | After Sept. 10, 
1908 3e eet a 24+ | 99.0] 73.0] 86.50 | 870.00 
July 31, 1908..... Aug. 19, 1908 20 | Sept. 30-Oct. 
26,1908) 2-66 42-68 | 99.0] 73.0 | 86.70 | 874.00 
Aug. 2,1908....- Aug. 22, 1908 21 Sept. 28, 1908 - - - 37 | 99.0] 73.0 | 86.26] 908.50 
Aug. 21, 1908....] Sept. 8, 1908 19 | Nov.13-26, 1908. 66-79 | 97.5 | 75.0] 83.73 | 774.00 
Aug. 25, 1908....] Sept. 12, 1908 AOE. i Seer Gore 8 250 62-75 | 97.5] 74.5 | 88.90] 777.20 
Aug. 26, 1908....| Sept. 14, 1908 740) (ee GOssecetgee 60-73 | 97.5] 74.5 | 83.60} 812.45 
Oct. 21, 1908. ... - - Mar. 11, 1909 142 After Apr. 24, 44+ | 85.0] 17.0 | 60.88 |2, 314.00 
O09 cae ene 
Sept. 20; 1910. -..| Nov..12?, 1910) | 54 (abowt)-| Feb. 20, 1911-22) 100\(@bowt) ||s2.524_|2-2 2 cole Sole ee 
OUT OF DOORS. 
Apr. 13-26, 1906 .| May 27, 1906 45 Aug. 15, 1906... - 80 | 93.0] 41.5 | 69.08 |1, 173.60 
Apr. 28,1906....| May 30, 1906 Chi Sse ose cahaocet Sern oeSackoes 93.0] 42.0] 71.72 | 947.76 
Before May 4,1906| June 5, 1906 Soe ieee een ae Ss $e) peor See One | MEMoren| ence) sect esicece =. 
May 17, 1906..... June 9, 1906 7 a RUE Sa IS CF on) [Oh SO WD OE 93.8 | 59.2] 76.90] 813.60 
Thelarva (Table XX XIIT).—The longevity of larvee in summer under 
the most favorable conditions was 80 days. Several lots are recorded, 
however, in which the longevity was much shorter, the average life 
being not far from 2 months. The last individuals of a lot of larvee 
from eggs deposited from August 4 to 6, 1907, and which com- 
menced to hatch August 25, died between January 3 and 10, 1908, 
thus having lived between 131 and 138 days. Christophers states 
that in nature the larve collect near the bottom of walls and wait for a 
dog to brush against the spot. 
Engorgement took place in as soon as 8 days; the greatest num- 
ber dropped from the third to the fifth days, and all dropped before 
the seventh day. Christophers found larve which he placed upon a 
dog to engorge and drop in from 3 to 4 days. 
Ae a Eps gk te 
