100 LIFE HISTORY OF NORTH AMERICAN TICKS. 
other lots lived from 16 to 55 days, at the end of which time they 
were put on hosts. 
Nymphs were found to attach readily to a bovine host very soon 
after being applied. Attempts to get collected nymphs which were 
partially engorged to reattach to cattle and guinea pigs were not 
successful. Similar results were obtained when attempts were made 
to attach to rabbits and cattle nymphs which had very recently 
molted from the larval stage. Inthethreelots of nymphs the engorge- 
ment of which is recorded in the accompanying table the shortest 
period of engorgement was 5 days, the longest 8 days, and the weighted 
average 6.9 days. All of the specimens were fully engorged when 
they dropped. 
TABLE XX XI.—Engorgement of nymphs of Hxmaphysalis chordeilis. 
Nymphs dropped—Days 
N following application. Total 
Date nymphs applied. Host. era number 
dropped. 
5 6 iG 
1909. 
INOW sere nae seem aein ec cisearoasseereres Bovine... . Ce BS 2A nee er 3 1 4 
INDY ices cee nese et ieee tees ar eee ees dots toees ee ee IG An ASe ae 2 2 
Ee) ae aE ls Re an? eae ae’ |:--d0 sia 5 1 pe fem nal ges 2 3 
The shortest molting period for nymphs in the 13 cases observed 
was 26 days. During this period the mean temperature was 68.05° F. 
and the total effective temperature 651° F. The longest molting 
period was 186 days at a mean temperature of 60.54° F. The lots of 
collected individuals varied from one-tenth to fully engorged. None 
of the specimens under one-half engorged was observed to molt to 
adults. The temperatures given are those recorded at the Dallas 
laboratory from the date the ticks were collected to the date when the 
first tick molted. 
The adult—Of a lot consisting of 4 males and 3 females which 
became adult between May 5 and 10, 1910, 2 individuals of each sex 
were placed on hosts, 2 males and 1 female being kept for a longevity 
test. One male and the female died on August 18, 1910, having lived 
about 100 days. The last male lived until March 11, 1911, or a period 
of 305 days. <A female in another lot was found to live between 131 
and 166 days after molting, and in a third lot a male lived between 
97 and 127 days. Unengorged adults remain inactive for long periods 
when kept in a tube, and it is sometimes difficult to induce them to 
crawl. One female which was fully engorged but not fertilized lived 
172 days, no eggs being deposited. 
A male and a female were placed on a bovine April 30, 1910. The 
female was found to be attached when examination was made 6 
hours later. The male failed to attach as did also two other males 
