116 LIFE HISTORY OF NORTH AMERICAN TICKS, 
for a short time, during which the chitin hardens; they then find 
females, with which they mate, or they may attach beneath engorged 
nymphs and await their transformation. 
Females have been found to engorge and begin dropping on the 
fourth day after molting. The longest period observed between the 
first nymphal molt and the dropping of the first female was 14 days. 
In a large number of infestations the minimum parasitic period (from 
the application of larve to the beginning of dropping of females) 
was 20 days. The maximum parasitic period was 59 days and the 
average was 32 days. 
TaBLE XL.—Parasitic period of Margaropus annulatus on bovines. 
: Period, adult | Period, attachment 
First molt. Second molt. Adults dropped. stage. to dropping. 
Larve Sq is | . 
i Zo AES 4 
applied. 38 = : on g 5 EI E 3 
: gs : z : 2| g g | I Es 
225 Biel Soc lee | OF Hoe |e | Bane Jae oiees 
4 [ax] . * 
a Neel oa leet 78 pers) Shey tee) see |e ie 
1907. 1907. |Days.| 1907. |Days.| 1907. 1907. Days. | Days. | Days. | Days.| Days. 
Feb. 16 | Feb. 23 falpMary 03 8 | Mar. 12 | Mar. 22 72 9 19 34 24 | 29 
July 12} July 18 6 | July 27 9| Aug. 1] Aug. 9 89 5 13 28 20 
1910. 1910. 1910. 1910, | 1910. 
Oct. 14 | Oct. 20 6 | Oct. 29 9} Nov. 5| Nov. 21 | 712 7 23 38 22) 30 
1911. 1911. 1911. 1911. 
Dec. 27 | Jan. 8 12 | Jan. 14 6 | Jan. 23 | Feb. 8} 760 9 25 43 27) 35 
1911. 
Mar. 15 | Mar. 23 Si) Apres ok 9} Apr. 10} Apr. 23 | ‘212 9 22 39 26 | 32.5 
LIFE CYCLE, 
At Dallas, Tex., the larve hatching from the entire mass of eggs 
deposited by a female have been found to survive for a period of 246 
days from the time hatching began. The larvee begin molting from the _ 
fifth to the twelfth day after application toa host. Thenymphs become 
engorged and begin molting from the thirteenth to the eighteenth day. 
Adults sometimes engorge and drop as soon as the fourth day after 
the nymphal molt. The minimum period from the attachment of the 
larve to the dropping of the first engorged female was 20 days and 
the maximum period was 59 days. Oviposition may commence on 
the day following dropping, but usually the preoviposition period is 
at least 3 days. In the summer, when the mean temperature was 
87° F., hatching began on the nineteenth day after the beginning of 
deposition. An effective temperature of at least 820° F. is required 
for incubation. The period from the dropping of the engorged 
females to the death of the last larve, or the nonparasitic period, 
varies from 28 days in summer to 279 days in fall, winter, and spring. 
In the southern part of the United States all stages of this tick may 
be found on hosts at any time during the year. 
