110 LIFE HISTORY OF NORTH AMERICAN TICKS. 
Males do not appear to remain attached to the host after the females 
have dropped. If they do not drop with the females they start out 
in search of another mate; in this search they frequently go from one 
dog to another. Their longevity on the host is at least several 
months. 
LIFE CYCLE. 
Oviposition may commence as soon as the third day, and as many 
as 2,616 eggs may be deposited. In August eggs may hatch in 19 
days, an accumulated effective temperature of 774° F. appearing to 
be required for their incubation. Larve may live for 131 to 138 
days while waiting for a host; they may engorge in 3 days and molt in 
6 days. <A total effective temperature of 235° F. is required to pro- 
duce this molt. During the winter nymphs may live for 6 months; 
they may engorge in 4 days after attaching to a host. In summer 
they may molt in 12 days, a total effective temperature of 500° F. 
being required. Adults may live as long as 204 days; they may 
become engorged in 6 days after attaching to an animal; fertilization 
takes place on the host. All stages of the tick may be found at any 
time during the year. However, they are less numerous after long 
continued drought. 
ECONOMIC IMPORTANCE. 
This species is perhaps the most important tick that attacks the 
dog. While restricted in its distribution to the Tropical and Sub- 
tropical life zones, it is widely distributed over the Old and New 
Worlds, in both of which it is the source of great annoyance to dogs. 
Its particular importance, however, lies in the fact that it is the active 
agent in the transmission of canine piroplasmosis. Fortunately 
this disease has not been introduced into the New World. It is, 
however, prevalent in certain sections of the Old World, particularly 
in India. The disease also occurs in South Africa, where it has been 
shown by Lounsbury to be transmitted by Hemaphysalis leach. 
Ce ee a es ee ree ae 
NATURAL CONTROL. 
While no particular investigation has been made of the predaceous 
enemies of the species, those attacking the cattle tick undoubtedly 
destroy this tick also. 
In 1908 a parasite was discovered which destroys large numbers of 
this species while in the nymphal stage. * This parasite, the second 
recorded as attacking ticks, was described by Dr. L. O. Howard 
(1908) as Hunterellus hookeri. In order to determine the percentage 
of parasitism, 100 engorged nymphs were collected at Brownsville, 
Tex., August 17, 1908, and an equal number from Corpus Christi on 
August 18, 1908. These were isolated in pill boxes in lots of 10 
each and kept on moist sand. Of the 100 collected at Brownsville, 27 
7 ty 
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