oo LIFE HISTORY OF NORTH AMERICAN TICKS. 
CANNIBALISM. 
A phenomenon closely related to cannibalism has been observed 
in a few instances. Hunter and Hooker (1907, p. 35) recorded an 
observation upon that habit. Among specimens of Margaropus 
annulatus which had been sent to the laboratory in pill boxes was 
found a male with its hypostome deeply inserted in the side of an 
engorged female. Another instance has come to our attention in a 
figure by C. A. Barber (1895) of Amblyomma variegatum (Hyalomma 
venustum) showing a male attached to the posterior end of an en- 
gorged female. 
In two instances in the course of our investigation Mr. Wood has 
observed adults of Ornithodoros turicata to attack and imbibe a large 
amount of blood from the body of a recently fed adult of the same spe- 
cies. The specimens from which blood was taken did not seem to 
be injured by the bite of their fellows. 
On April 18, 1910, a box was received at the laboratory which 
contained two females of Dermacentor venustus taken on a horse at 
Lakeside, Wash. When received the smaller female, which was 
shehtly engorged, was attached to the fully engorged individual at a 
point between the genital opening and the coxa. In the evening of 
April 18 the small female was found to have detached, leaving the 
other somewhat distorted in the region of attachment. The injured 
female began depositing on April 21, but died a few weeks later after 
laying but 150 eggs, all of which were shriveled and failed to hatch. 
MULTIPLICATION. 
There is a great variation in the rate of multiplication of ticks, due 
to the fact that some species pass one or both molts while upon the 
host, while others drop for both. The ticks which drop for both 
molts must find a host three separate times before eggs can be depos- 
ited. Thus their chances of becoming adult are lessened, as compared 
with the species which pass both molts upon the host, by the propor- 
tion of 3 to 1. Those which drop to molt have overcome this great 
disadvantage to some extent through a greater resistance to heat, 
cold, etc., while awaiting the host, and through depositing larger 
numbers of eggs. It is well known by zoologists that the number of 
offspring produced by an animal is in inverse proportion to the 
chances of their reaching maturity. Thus with ixodid ticks many 
thousands of eggs are produced. As will be seen by the accompanying 
table the greatest number of eggs recorded by us as deposited by a 
single individual was 11,265, which were deposited by Amblyomma 
maculatum. Mégnin (1904) has recorded 12,000 eggs as being depos- 
ited by Hyalomma xgyptium, Barber (1895) 20,000 as deposited by 
Amblyomma variegatum, and Lounsbury (1899) estimates the maxi- 
