THE RABBIT DERMACENTOR. 161 
be most abundant in western Texas and in New Mexico. Larve and 
nymphs have also been taken at Monclova, Mex. 
LIFE HISTORY. 
No observations on the biology of this species have been previously 
published. 
The egg (Table LXXI).—In July at a mean temperature of 85° F. 
oviposition commenced as soon as the fifth day after dropping. Four 
of 7 ticks which dropped engorged during July and early August com- 
menced oviposition on the fifth day, the three remaining ones com- 
mencing a day later. The average oviposition period of 7 females 
observed in July and August was 15.9 days. The minimum oviposi- 
tion period was 11 days, within which time 855 eggs were deposited; 
the maximum, 26 days, during which period 3,247 eggs were laid. 
The maximum number of eggs recorded for the species is 4,660. The 
female which made this record deposited 918 eggs during one day. 
The females died in from 1 to 6 days after deposition was completed. 
One of the 7 engorged females upon which these counts of eggs were 
made was collected on a rabbit, while the other 6 females were engorged 
upon bovines. The measurements of the 6 were as follows: 10 by 7 
by 4 mm., 12.5 by 9 by 6.5 mm., 12 by 8.5 by 6 mm., 11 by 7.5 by 
4mm., 10 by 7 by 5mm., and 10 by 7 by 3.5 mm., respectively. 
The shortest incubation period was 20 days, the mean tempera- 
ture during this period being 85° to 86° F. A total effective tempera- 
ture of at least 850° F. appears to be required for embryonic 
development. 
TaBLE LXXI.—Jncubation and larval longevity of Dermacentor parumapertus margin- 
atus. 
Temperature during incubation. 
| 
: Minimum Larval | 
Eggs de Hatching be- | - All larve ‘ 
a gan. ats -g dead. longev- | | arins. | Average | otal 
period. ity. | Maxi- | Mini- daily | effective 
| mum | mum mean. oe 
Days. | Days. te I. °F, "k 
June 30,1908 | July 23,1908 Ye Ee Seat Tes. aE Poe eee 95 70.0 81.1 954. 25 
July 2,1908 | July 24,1908 ft RSA 8 ER te 95! 70.0 83.1 959. 75 
July 18,1908 | Aug. 8,1908 22 | Jan. 25,1909 170 99 76.5 85.5 935. 75 
July 20,1908 | Aug. 10,1908 22 | Nov. 30,1908 102 99 73.0 85.4 916.75 
July 22,1908 | Aug. 12,1908 22 | Mar. 6,1909 223 99} 73.0 85.7 922. 75 
July 24,1908 | Aug. 14,1908 22 | Mar. 12,1909 7 99 73.0 85.9 944.75 
July 26,1908 j.....do....... 20 | Feb. 10,1909 197 99 73.0 86.2 863.75 
July 27,1908 | Aug. 16,1908 21 | Oct. 26,1908 71 99 73.0 86.3 909. 00 
July 28,1908 | Aug. 17,1908 21 | Feb. 15,1909 7 99 73.0 86. 4 911. 50 
July 30,1908 | Aug. 19,1908 21 | Mar. 12,1909 222 99 73.0 86. 7 917.25 
Aug. 3,1908 | Aug. 22,1908 Dec. 6,1908 106 99 73.0 86. 2 | 863. 50 
Aug. 5,1908 | Aug. 24,1908 20 | Mar. 9,1909 214 99 73.0 85.1 857.25 
Aug. 8,1908 | Aug. 28,1908 21 | Feb. 17,1909 167 96 73.0 - Bs S878. 25 
Aug. 14,1908 | Sept. 4,1908 22| Feb. 5,1909 96] 75.0 4 908. 50 
Aug. 16,1909 | Sept. 8, 1909 24 rae ss 193-221 110 77.0 89.38 | 1,112.75 
,191 
Aug. 14,1909 | Sept. 3,1909 21 | Nov. 18,1909-| 76-144 110 77.0 89.51 | 976. 25 
Jan. 25, 1910 
The larva (Tables LXXI-LXXIII).—The greatest longevity of 
larve observed by us was 227 days. Engorgement has taken place as 
soon asthe fourthday. Asisshown in the last record in Table LXXII, 
21448°—Bull. 106—12——11 
