THE TROPICAL HORSE TICK. 201 
result of this habit great numbers of ticks reach maturity and repro- 
duce, but fortunately there has also resulted a great decrease in the 
power of the larve to withstand periods of fasting. 
As is shown in Table XCVII, larve may engorge and molt as soon 
as the eighth day after attaching to a host. The longest period from 
larval attachment to molting was 16 days. 
The nymph (Table XCVII).—In two of the three lots recorded in 
Table XCVII nymphs became engorged and began molting on the 
seventeenth day after being applied to the host as larve. In the 
third infestation nymphs began molting to adults on the twenty- 
fourth day after being applied. The period from the molting of the 
first larvee to the molting of the first nymph was 8 days in one instance 
and 9 days in the other two cases observed. In one instance the 
nymphal period appeared to have been only 7 days. 
The adult (Table XCVII.—The mating of males and females of this 
species, which molted on the host on the same day, took place as 
soon as the second day following and was continued until the engorged 
females dropped. This habit appears to be similar to that of JJar- 
garopus annulatus. A male Amblyomma americanum has been found 
attached beneath a female of this species, the ventral surfaces being 
in apposition as though in copulation. The sexes remained in this 
relation for only a short period. Likewise males of Jlargaropus 
annulatus australis and Dermacentor variabilis have remained mated 
with females of the tropical horse tick for a number of days. Several 
females have engorged and dropped, apparently without having been 
fertilized. One unfertilized female remained attached from the time 
it molted on May 6 until May 26, when it dropped unengorged. 
A second unfertilized female which molted July 18 dropped August 
11 when only slightly engorged. 
Females have engorged as soon as 9 days after molting or 26 
days after attachment to the host as larve. The longest engorgement 
period observed was 23 days after molting, or 41 days after being 
applied to the host as a larva. Females collected at Brownsville, 
Tex., in November have reattached to a host 3 days later. A slightly 
engorged female thus transported attached and dropped engorged 7 
days later, measuring 10 by 8 by 5 mm. Newly molted females 
reared from engorged nymphs taken from a horse have attached to 
a bovine. One thus attached on December 9, 1907, dropped en- 
gorged 11 days later, measuring 10 by 7 by 4.5 mm. A second, 
attached at the same time, dropped after 15 days of attachment, 
measuring 10.5 by 7.5 by 4.5 mm. 
A male has been found to remain upon a host 84 days after the first 
female dropped, or 99 days after attachment as a larva. At the end 
of this period it was found dead in the retaining bag. Upon another 
host a male remained for 72 days after the last female dropped, or 86 
