LOCOMOTION AND DISSEMINATION, 33 
mum number deposited by Amblyomma hebreum at 20,000. The 
comparative reproductive capacity of the ticks which we have studied 
is shown in Table IT. 
Tape Il.—Reproductive capacity of the species of ticks studied. 
Number of eggs deposited. 
Number 
Species. of ticks 
recorded.| Maxi- | Mini- | Aver- | Maximum number recorded 
mum. | mum. | age. by other observers. 
Amblyomma americanum..-..........- 12} 8,330 947 | 3,054 | 6,519 (Morgan, 1899). 
Amblyomma cajennense...........-... 13 | 4,789 | 2,384] 3,536 | 7,240(Williams by New- 
stead, 1909). 
Amblyomma dissimile...............-- 2] 1,655] 1,573 | 1,614 | 1,784 (Newstead, 1909). 
Amblyomma maculatum.............- 7 | 11,265 | 4,560] 8,282 
Amblyomma tuberculatum..........- 2| 5,481 | 2,197] 3,839 
PATAS MINNA ULIS s vo ten Sees nee aoa ee 21 874 252 537 
Dermacentor Mitens = = \..0<20 5-2 <n2c cen 12 | 3,392}; 2,149] 2,784 
Dermacentor occidentalis ...........-. 6} 4,555 | 2,373) 3,247 
Dermacentor parumapertus margina- 6 | 4,660 855 , 002 
tus. 
Dermacentor variabilis 
Dermacentor venustus........ 
Hemaphysalis leporis-palustr 
; 7,378 (Morgan, 1899). 
, 422 | 4,820 (Cooley, 1909). 
Ixodestkineiae. 2 bs. ecieesee nk te 3} 4,706} 1,556] 3,179 
Exod esiscapulanist: 2 afin sc antoet -2 2 amet 11} 3,000] 3,000} 38,000 y 
5,105 (Graybill, 1911). 
Margaropus annulatus................ 10 | 4,547 | 2,127] 3,424 ger Newel and Dougherty, 
1 
Margaropus annulatus australis......- 5 | 3,975 | 2,492] 3,072 | 3,046 (Rohr, 1909). 
Ornithodoros megnini................ 13} 1,207 358 760 
Rhipicephalus sanguineus............. 12] 2,616 360 | 1,602 
1 Number of eggs estimated. 
Figuring, on the basis of four generations in the Gulf States, that 
half of the resulting adults are females, and that 2,000 eggs are de- 
posited by each female, Mayer (1906) has estimated that two Mar- 
garopus eggs carried over the winter and hatched by April 15 would 
increase to a total of 6,750,000,000 ticks by October 15, if all the 
females found hosts and developed. It is at once seen that this is a 
theoretical estimation, as only a small percentage of the ticks ever 
finds a host. 
LOCOMOTION AND DISSEMINATION. 
Experiments have been made by different persons to determine 
the part that locomotion may play in the dissemination of replete 
females of the cattle tick. Hunter and Hooker (1907) found them 
to travel 123 inches in the course of 52 minutes, always traveling 
away from the light. Engorged females of Dermacentor venustus 
have been observed by us to crawl as far as 33 inches in 4 minutes. 
They seem to crawl in the direction in which they are headed 
without regard to light. The engorged females of all species 
usually crawl into the first obscure nook, crack, or crevice that 
they find, and for this reason usually do not travel far from 
where they drop. Little has been done to determine the distance 
21448°—Bull. 106—12 3 
