FAMILY ARGASIDAE 



INTRODUCTION 



Argasid ticks Cfamily Argasidae) are called haim ( p— -r^ ) in 

 Stttiani Arabic, They are leathery or ""soft'" ticks that secrete 

 themselves in soil or in crevices, come oirt to feed for a short 

 while, ajid then retreat to their hiding place. Two of the several 

 argasid genera, Argas and Ornithodoros , are common in Africa, The 

 term argasid should riot be construed to refer to the genus Argas 

 alone. The sole African representative of a third argasid genus, 

 Otobius , an ear tick, has been introduced from America into South 

 Africa, Madagascar, and parts of Central and East Africa, but is 

 not known to occur in the Sudan. A variety of argasids occur through- 

 out most of the tropics and subtropics of the world. Fewer species 

 live in temperate areas and very few inhabit arctic climes. Two spe- 

 cies presently are distributed widely as a resvilt of human transpor- 

 tation of domestic fowls, 



Argasid eggs, deposited at intervals in small batches and total- 

 ling only a few hundred, are laid in niches where females seek shel- 

 ter. Chances that hatching larvae will find a favoiirable host near- 

 by are reasonably good. Larvae of the two Ornithodoros species in 

 the Sudan are nonmotile and do not feed; this feature of their life 

 cycle is unique in the genus. Larvae of Argas feed on birds or bats, 

 or less commonly on other animals, and remain on the host for several 

 days to several weeks. Nymphs and adults of both genera feed for 

 only a few minutes to a few hours at most, in marked contrast to the 

 longer attachment time of most nymphal and adult ticks of the family 

 Ixodidae, There are at least two and sometimes as majiy as six or 

 more nymphal instars. Argasid adults take several blood meals, each 

 of which is usually followed by a rest for digestion and, in the 

 female, for oviposition. The genus Otobius , mentioned above, has 

 more highly specialized feeding habits . 



Argasid ticks are of considerable economic and medical impor- 

 tance in many parts of the world. However, at the present time they 

 are apparently of less importance in the Sudan thaji in many other 

 parts of Africa. As transportation facilities improve and urban 

 areas become larger smd more settled, it is to be expected that Or- 

 nithodoros moubata will become more widely established in human "Eabi- 

 tations of southern Sudan, 



- A8- 



