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 XXXII.—Jncubation and larval longevity of Rhipicephalus sanguineus. 
IN THE LABORATORY. 
Temperature during incu- 
bation. 
~ | Minimum 
Eggs deposited. ee incubation | All larve dead. Larval lon- es 
gan. ad gevity. Aver- 
1 eS Maxi-} Mini-| age Ba 
mum.|mum.| daily prom 
mean e 
Days Days. cole oF. Sei. ae 
Mar. 31, 1908....- May 10, 1908 NTIS RR Coen Bes ore reel 9 Se = 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 OT ~ | ciercteeisetetsteinaie taints terete inicletaievstere 87.0} 47.0 | 72.33 |1, 082. 25 
Apr. 22, 1908....} May 26, 1908 OO) y He oet aceite als eee so aeles 87.0 | 47.0] 72.05 | 986.25 
July 7; 1908: ..<.5.- July 27,1908 21 Oct. 7, 1908....- 72 | 95.0] 74.0] 83.99 | 860.50 
July 29, 1908... .- Aug. 17, 1908 20 After Sept. 10, 
OOS? 22s ae ates 24+ 99.0] 73.0} 86.50 | 870.00 
July 31, 1908....- Aug. 19, 1908 20 Sept. 30-Oct. 
265 1008). . -- <5 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 Dal ere Goes 62-75 | 97.5 | 74.5 | 83.90 | 777.20 
Aug. 26, 1908....] Sept. 14, 1908 op) ml eeees dow eee 60-73 | 97.5 | 74.5] 83.60 | 812.45 
Oct. 21, 1908... .. Mar. 11, 1909 142 ilies Apr. 24, 444 85.0 | 17.0 | 60.88 |2, 314.00 
YO ee NeRES 
Sept. 20, 1910....| Nov.12?,1910 | 54(about).| Feb. 20, 1911.-..| 100 (about) |.......|....---|.-.--.-|.----..- 
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 88) |Esee aco acchodsseas|Sosncdonedss 93.0 | 42.0 | 71.72 | 947.76 
Before May 4,1906) June 5, 1906 SOae We eet. es eh ese ssfh ct c cele fosees | Eamon | Reena | oe ereee 
May 17, 1906....- June 9, 1906 lh oa | oR ERE SE So 93.8 | 59.2 | 76.90} 813.60 
Thelarva (Table XX XJIT).—Thelongevity 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 larve 
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 larvee collect near the bottom of walls and wait for a 
dog to brush against the spot. 
Engorgement took place in as soon as 3 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. 
