Ixodoidea, or Ticks 65 



sulphur in warding off the attacks of Trombidiidas, it is astonishing 

 to find that Lounsbury has kept adults of Argas persicus for three 

 months in a box nearly filled with flowers of sulphur, with no apparent 

 effect on them. 



We have already called attention to the occasional serious effects 

 of the bites of this species. While such reports have been frequently 

 discredited there can be no doubt that they have foundation in fact. 

 The readiness with which this tick attacks man, and the extent to 

 which old huts may be infested makes it especially troublesome. 



Otiohius (Ornithodoros) megnini, the "spinose ear-tick "(figs. 47, 48), 

 first described from Mexico, as occurring in the ears of horses, is a 

 common species in our Southwestern States and is recorded by Banks 

 as occurring as far north as Iowa. 



The species is remarkable for the great difference between the 

 spiny nymph stage and the adult. The life history has been worked 

 out. by Hooker (1908). Seed ticks, having gained entrance to the 

 ear, attach deeply down in the folds, engorge, and in about five days, 

 molt ; as njTnphs with their spinose body they appear entirely unlike 

 the larvas. As nymphs they continue feeding sometimes for months. 

 Finally the nymph leaves the host, molts to form the unspined adult, 

 and without fiu-ther feeding is fertilized and commences oviposition. 



The common name is due to the fact that in the yoimg stage the 

 ticks occur in the ear of their hosts, usually horses or cattle. Not 

 uncommonly it has been reported as occurring in the ear of man and 

 causing very severe pain. Stiles recommends that it be removed by 

 povuing some bland oil into the ear. 



Banks (1908) reports three species of Ornithodoros — 0. turicata, 

 coriaceus and talaje — as occurring in the United States. All of these 

 attack man and are capable of inflicting very painful bites. 



Ixodidse 



The ticks belonging to the family Ixodidse (figs. 49 and 50) exhibit 

 a marked sexual dimorphism. The capitulum is anterior, terminal, 

 instead of ventral as in the Argasidse; the palpi are relatively rigid 

 (except in the subfamily Ixodinas) , with rudimentary fourth segment ; 

 scutum present; eyes, when present, dorsal, on side of scutum. The 

 spiracles are generally large, situated well behind the fourth coxae ; 

 coxce generally with spurs; pulvilli always present. 



In habits and life history the typical Ixodidse differ greatly from 

 the Argasidas. They are relatively short-lived, though some recent 



