58 LIFE HISTORY OF NORTH AMERICAN TICKS. 
In August, at a mean temperature of 84° F., molting commenced as 
soon as the ninth day following dropping, an effective temperature of 
369° F. being required. 
The adult! (Table X).—The males and females may be readily dis- 
tinguished by the shape of the genital orifice, that of the former being 
crescent shaped while in the latter it is merely a transverse slit. 
The longevity of the adults is surprisingly great. From a lot of ticks 
collected March 24, 1906, which were kept confined in a vial with a 
cork stopper, one lived until September 38, 1907, a period of 17 
months. In two miscellaneous lots of some 50 or more ticks collected 
May 12, 1906, and kept in large vials with paper strips, the last 
individual died about October 12, 1908, having lived for 2 years and 
5 months. Some individuals in nearly all of a large number of lots 
of collected ticks have been found to live more than one year. 
Females lived from 5 to 13 months when engorged soon after they 
had molted to the adult stage and immediately after each deposition. 
One specimen, which was engorged three times, lived 18 months, 
depositing 244 eggs in the meantime. 
The longevity of adults which have not fed after molting appears 
to be slightly less than when some food has been taken. One in- 
dividual, which molted to an adult August 16, 1908, was still alive 
May 27, 1910, having lived over 214 months. However, most of the 
specimens observed died between 4 and 12 months after molting. 
Laboulbéne (1881) has reported the fowl tick to live (unfed) for 
more than three years. 
Fertilization is accomplished by means of a spermatophore, which 
is deposited by the male at the genital aperture of the female, follow- 
ing the introduction of the hypostome of the male into the genital 
opening of the female. The act of copulation is described in some- 
what greater detail on page 30. 
The adults engorge repeatedly and oviposition follows each engorge- 
ment, with few exceptions. Thus, as shown in Table IV, we have 
found females to engorge as many as seven times, each engorgement 
being followed by the deposition of eggs. Lounsbury (1903a) has 
found females to engorge as many as seven times and to deposit fol- 
lowing six engorgements. As has been stated, Nuttall and Warburton 
found that two-thirds of the nymphs and adults engorge within 30 
minutes. We have not determined the exact time required for 
engorgement. However, in one case 38 per cent of a large number 
of adults applied to a fowl had dropped engorged when examination 
was made an hour and a half later. Usually engorgement takes 
place at night, but when fowls are exposed to their attack in dark 
1 Our system of numbering adult ticks of this species, in order that they might readily be identified 
after engorging, consisted in the docking of a part of one or more legs. This apparently has no ill effect 
upon these ticks. 
