36 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 1 



It is well known that in order to develop, it is necessary for the 

 ticks to attach to and suck blood from some animal and that unless 

 such host is found within a certain period, which varies mainly with 

 the temperature and precipitation, that it will starve. Upon this 

 knowledge as related to Margaropus (Boophiliis) annulatus is based 

 the method of freeing pastures by the so-called rotation system as 

 first worked out by Prof. H. A. Morgan. 



All ticks pass through four distinct life stages: the egg, the larva 

 or seed-tick, the nymph or yearling-tick, and the adult or sexually 

 mature stage. The female, following the engorgement of blood, be- 

 comes greatly distended and drops to the ground, crawls to some pro- 

 tective covering, and soon commences the deposition of large numbers 

 of eggs. In the course of a few weeks these hatch into the six-legged 

 larvae or seed-ticks, which await the coming of, or in some species 

 crawl to, the host. Ha\'ing found a host they attach and soon engorge 

 with blood, after which they either molt while attached or drop and 

 pass a short period of quiescence during the metamorphosis, then 

 appear in the eight-legged nymph stage. 



A second engorgement takes place and the ticks either molt attached 

 or drop as before, pass a period of quiescence, then molt and appear 

 in the adult stage. Another, the third engorgement, is followed by 

 dropping and oviposition, and the generation is completed. In the 

 Spinose Ear Tick, Ornithodoros megnini, we find a variation from 

 this. It drops as a nymph and, following the molt, without engorg- 

 ing as an adult, commences oviposition. In the genus Argas a second 

 nymphal engorgement and molt takes place. In the family Ixodidoe 

 death follows the completion of oviposition, but in the genus Argas 

 of the family Argasidae repeated engorgement takes place, followed 

 each time in the female by the deposition of eggs. 



The appearance of the active stages of the ticks varies greatly from 

 the unengorged to the gorged, excepting in the male, which does not 

 engorge with blood, but seems to exist upon serum. Because of this 

 variation in appearance, individuals of the same species have been 

 described as different species. The nymphal stage can be separated 

 from the adult by the absence of the genital pore. The sexes can 

 only be distinguished after the final molt, except in a few species in 

 which the high color markings can be seen through the nymphal skin 

 a day or two prior to molting. As adults they are separated readily 

 in the Ixodidae by the shield or scutum, which in the female covers 

 but a small part of the dorsum, but in the male completely covers it. 

 In the Argasidae the sex can only be distinguished by the shape of 

 the genital pore, which in the male is crescent shaped, while in the 

 female it is merely a transverse slit. 



