DEVELOPMENT OF THE IXODID&. 73 
PREOVIPOSITION. 
Following engorgement the female drops from the host, crawls to 
some protective covering, as into sand, cracks in the soil, beneath 
vegetation, litter, boards, or into cracks and crevices in buildings. 
In summer oviposition may commence as soon as the day following 
dropping, but usually the preoviposition period is of somewhat greater 
duration. In cold weather it may be delayed for as long as several 
months. 
THE EGG. 
The deposition of eggs continues in summer from one to two or 
more weeks, while during the colder months it may continue from 
one to several months. With the ixodid ticks oviposition occurs 
but once, during which time from one to many thousand eggs may 
be laid; with the completion of oviposition the female dies. The 
shortest incubation periods observed in the several species studied 
vary from 16 to 91 days. The longest incubation period recorded 
was 202 days. Temperature is the principal influencing factor, 
although humidity has some effect, particularly on the percentage of 
egos hatching. 
The manner of oviposition by Ixodes was first described correctly 
by Gené (1845), and later by Bertkau (1881). Curtice (1892, p. 242) 
first described the process in Margaropus annulatus, Lewis (1892) in 
Amblyomma coronatum, and Wheler (1906) in Ivodes ricinus. A de- 
tailed account of the process in M. annulatus has been given by Cush- 
man as reported by Hunter and Hooker (1907, p. 16). Lewis’s 
report of observations and that of Wheler are accompanied by illus- 
trations and Cushman has made a drawing which we here present 
(see p. 127, fig. 9) of the organ protruded by Amblyomma tuberculatum. 
During oviposition the capitulum is retracted and a viscid vesicle 
to which Gené gave the name vesica biloba is protruded from between 
the capitulum and the scutum, from the lateral extremities of which 
two elevations are thrown out to be lengthened by evagination into 
two horns, lobes, or papille, as they have been described, which 
receive the eggs from the protruded oviduct. The glands of this 
vesicle secrete a viscid substance with which the lobes coat the eggs, 
thus causing them to adhere in a mass, and furnishing protection 
from drying. Gené found that eggs laid after destroying this sac, 
thus preventing the eggs from being covered, dried up and would 
not hatch, while others, newly laid by the same female and coated, 
hatched. Our observations appear to confirm those of Gené. In 
the case of the specimen of A. tuberculatum here figured, this sac 
was accidentally injured, resulting in the deposition of eggs which 
soon became dark and shrunken. 
