THE BIOLOGIES AND HABITS OF TICKS 431 



from the host the greater part of the time, imbibing blood rapidly when 

 favorable opportunity offers, such as when the hosts are at rest at night. 

 The first or seed tick stage of this group of ticks, however, usually remains 

 on the host for several days. The adults of this family partake of blood 

 meals several times and the females deposit a number of batches of eggs. 

 The total number of eggs deposited is usually much smaller than in the 

 case of the ticks in the other family. 



Among the Ixodid ticks we find but one species wliich has the habit 

 of feeding rapidly, as in the Argasidae. In the other species each stage 

 remains on the host for at least several days. Even in the same genus, 

 however, we find widely diff'erent habits as regards feeding. There are 

 some forms in which the larvae and nymphs leave the host for molting. 

 In several species molting takes place on the host and the tick does not 

 drop off until it has become replete as an adult, while in still other 

 instances, the first molt takes place on the host and the second on the 

 ground. In all cases in this family the engorged females deposit a large 

 number of eggs and die soon after. In most species copulation takes place 

 on the host. The males may remain some time after the females have 

 dropped. In certain species of the genus Ixodes, however, it appears that 

 the males never attach to the host, but remain in the places frequented 

 by the host and when the females drop off they are fertilized by them. 

 A few species have been found to deposit fertile eggs without the inter- 

 vention of the male. The eggs of practicallj' all Ixodids are deposited in 

 a single mass in some protected place. They hatch almost simultaneously 

 in a few weeks' time and the larvae or seed ticks usually crawl upon vege- 

 tation and there await the passing of a suitable host. In the case of those 

 species which drop from the host for each molt, sometimes spoken of as 

 three-host species, it is necessary for the ticks to secure a host on three 

 different occasions, hence undoubtedly increasing the mortality before 

 maturity is reached. 



Many species show a predilection for attachment to certain regions 

 of the host. Structure or habits are sometimes modified to fit the condi- 

 tions under which the ticks live on the host. There is a tendency with all 

 ticks to choose the more tender portions of the skin upon which to attach. 

 Hence with many of our common forms we find groups of ticks between 

 the forelegs, on the brisket or the inguinal region. The habit of attaching 

 in the ears has already been mentioned in connection with Ornithodoros 

 megnini (Duges) Neumann. Tlie tropical horse t\c\i, jyermacentor iiitens 

 Neumann, also has this habit well developed. The Gulf Coast tick, Am- 

 hlyomma macidatum Koch, is usually found in the ear but never in the 

 deeper portions of that organ. On small animals there is also frequently 

 exhibited a tendency of the ticks to attach in the region where they are 

 least in danger of being destroyed by scratching or biting. 



