78 LIFE HISTORY OF NORTH AMERICAN TICKS. 
16 days, respectively, after collection. The eggs deposited were not 
counted, but it was estimated that at least 3,000 had been deposited 
by one of the ticks. A well-engorged female collected on a cow at 
Dallas, Tex., November 24, 1908, began depositing on December 11, 
thus having a preoviposition period of 17 days. 
Fic. 3.—The black-legged tick, Ixodes scapularis: Distribution in the United States. The large dots 
show localities where the species has been collected in our investigation. The small dots indicate 
the probable range of the tick. (Original.) 
In the laboratory at a mean temperature of 61° F., eggs deposited 
January 6 commenced hatching on March 17, an incubation period of 
72 days. An accumulated effective temperature of 1,318° F. was 
required for their incubation. 
EE 
