28 NORTH AMERICAN FEVER TICK AND OTHER SPECIES. 
due to the fact that, in light infestations with widely scattered ticks, 
fertilization is less likely to take place than in other cases where the 
males may find the females more readily. We have beer unable to 
determine that unfertilized females occupy longer in development 
than those that are fertilized, but our impression is that they do. 
The table also shows that the principal variation in the time of 
development of the ticks of the same infestation takes place not in 
the larval or nymphal but in the adult stage. 
Tasuie VIL.— Development of Margaropus annulatus on steer at Dallas, Tex. 
i q I 
| Adults dropped. ere iNtam- 
\iNtinai | eee ee ea Re Mini- Wor 
| 
Period from 
Ap- ntetead| | | 
: Mini- | | | mum | attachment to 
es When First | mum |} Second se ta pe- | Es dropping. 
-*" | applied. | molt. {larval} molt. oh ena riod | =| 
tion| “PI phal | First. Last. Gaute| ed or = 
stage. | | 
No. | 8 | stage. stage. 17P- Maxi- Mini-| Aver- 
ped. mum.mum.) age. 
|= | 
| | \ 
1905. Days. Days. | \Days.| \Days. Days. Days. 
1 | Aug. 16 | Aug. 28 12 | Sept. 2 | 5 | Sept. 15 | Sept. 274 WS] BON sD 30 36 
2 | Sept.27 | Oct. 4 FEM (Oye Ay 8 | Oct.' 21 | Nov. 3} 9 10 42 24 33 
3 | Nov. 11 | Nov. 22 11} Nov. 28 6] Dee: 8) Jan. 9)" 10 13 59 27 43 
| | | 
1906. | | | 
4| Jan. 16] Jan. 25} 9) Feb. 3] 9 | Feb. 17 | Mar. 8 | 14 11 dl 32 41.5 
5 | May 22 | May 31 9| June 6] 6 | June 14} June 30 | 8 95) < 39 23 31 
Gol we dull 9) | eee ee ee dnalyaedG | eee July 24] Aug. 5 8 | Sal aaron 25 31 
7} Aug. 2 |Aug.10-11 8-9 | Aug. 18 7-8 | Aug. 25) Sept. 11 7 14} 40 23 31.5 
8 | Sept. 5] Sept. 12 7 | Sept. 22 10; Sept. 26 | Oct. 6 4} 236 31 21 26. 5 
9 | Oct. 6} Oct. 14 | 8 | Oct. 21 7 | Oct: 305) Now: 12) 09) 200) |) 37) )|ee4 aso n 
10 | Nov. 29 | Dec. 8 | 9 | Dec. 14 67); Dees 22) Jam.) 8 55 33 23 28 
1907. | | | 
ITE AE oe IEP AE Hoke ts) 7| Jan. 14 6| Jan. 24 | Feb. 3 | 10 35 33 23 27.5 
| 
a Removed. 
DEVELOPMENT ON HOST. 
When the larval ticks find themselves on the host they rapidly dis- 
appear in the hair and attach themselves to the skin. They are 
principally found on such parts as the legs, belly, and dewlap that 
come in contact with the bunches on the grass, but may be found on 
any part of the host. In cases of severe infestation they practically 
cover the entire surface of the body, even the eyelids being infested. 
In from 7 to 12 days the larval ticks molt and enter the nymphal 
stage, in which they have eight instead of six legs. The nymphal 
stage is further distinguished from the larval stage by the presence of 
a pair of large stigmata quite in contrast to the rudimentary organs 
of respiration of the larva. 
The second molt (from the nymphal to the adult stage) occurs in 
from five to ten days after the first. _The nymph can be distinguished 
from the adult, which it resembles very closely, by the absence of any 
genital opening. The process of both molts is undergone by the 
females while the hypostome is firmly inserted in the skin of the host. 
The shed skin splits open along either side and drops off in two scale- 
like pieces. A portion of skin from the capitulum is also shed at the 
