of additional field study is required to answer many questions 

 concerning the life cycle of R. s. simus . This tick and H. 

 leachii are the only ubiquitous African species that in tlieir 

 immature and adult stages, respectively, feed first on nest- 

 inhabiting rodents and then on larger animals. More rigid 

 field observations, besides being a most pleasurable occupa- 

 tion, should be easily accomplished. 



In the following paragraph the question of where the female 

 oviposits is raised. In this connection, Howard's (1909B) ob- 

 servation of an unengorged male and female of R. simus (« R. 

 ecinctus ) mating on the leaf of an Acacia thorn tree on the 

 Zambesi River is of special interest (although the possibility 

 of misidentification of these specimens must be considered). 

 Almost invariably, rhipicephalid ticks mate on the host, as 

 do most other ixodids. Howard's note indicates the necessity 

 of further research to determine whether R. s. simus possesses 

 a unique type of mating and egg laying, and,~if so, whether 

 this is a constant or an exceptional phenomenon, and whether it 

 is associated with an ability of larvae to seek out their pre- 

 ferred habitat and hosts rather than waiting for a passing 

 rodent , 



Mating observed by J. B. Walker (correspondence) in Kenya 

 has been of the ordinary rhipicephalid type, on the host. Walker 

 also says that engorged females that have already dropped from 

 the host will mate with males that have been feeding on the same 

 host and then removed and placed with these females. This might 

 be merely a mating act and not initial or essential fertiliza- 

 tion (HH), for generally, it appears, female engorgement is not 

 complete or normal imless copulation has been effected. 



Ecology 



From Roberts' (1935) studies in the Nairobi area it appears 

 that the immature stages of R. s. simus prefer slightly subsurface 

 rodent nests rather than dee'per~nests of the same and of other 

 kinds of rodents. The grass rat, Arvicanthis , is possibly the 

 most important immature stage host. It is not known whether 

 larvae actually seek out the nest and attack the animal there, 

 or whether they attach to a rodent wandering in search of food 

 and are then carried to any nest that their host might be in_ 



- 7A6 - 



