G. H. F. Nuttall 
51 
appears reasonable to suppose that when they infest human dwellings 
it is because of birds being harboured there. The birds on which the 
ticks have been found are nearly all domesticated. The natural hosts 
of persicus and reflexus are commonly fowls and pigeons which doubtless 
have served to spread the tick amongst other birds in their vicinity. 
The thin skin of the bird seems peculiarly adapted for the successful 
attack of the small larval tick, and the nesting or roosting habit of the 
birds permits the ticks to drop off in situations adapted to the feeding 
and other life habits of the nymphs and adults. Both species in their 
mature stages are essentially night feeders, that is, they feed when the 
birds are in the dark and asleep, and the ticks retreat into crevices and 
dark places during the ylay-time. Where the ticks attack man they do 
so at night-time. I assume that 0. talaje var. capensis, which has been 
found in penguin’s and other birds’ nests, will be found to have a 
similar life-history to the above; the larvae should be found on the 
birds in localities infested by the tick. 
Argas vespertilionis has never been found on other animals than 
batsh Here we have a host which retreats to dark places during the 
day-time. The retreats of bats (hollow trees, beneath mofs of houses, 
in caves and grottoes) are more or less permanent dwellings where the 
ticks find shelter very much as do the Argasids above mentioned which 
attack birds. It is clear that to secure the adult stages of this tick the 
habitats of bats are the places in which to search for them. 
Group 2. 0. mouhata and 0. savignyi. 
In this group the larvae are inactive, and the first stage nymph 
attacks the host. This nymph feeds as rapidly (in the case of mouhata') 
as does the adult, f.e. in 10 minutes to one hour. Ornitliodorus mouhata 
and savignyi seem to be peculiarly adapted to their hosts and the habits 
of their hosts. All of the latter, i.e. man and the domesticated animals 
possess thick skins. Man appears to be the chief host, at any rate of 
mouhata. The hairle.ss human skin, coupled with man’s ability to 
remove his ectoparasites, renders prolonged parasitism difficult. Man 
herds his animals into a limited space in immediate proximity to his 
dwellings or resting places along routes of travel. Both species live in 
hot dry climates where thei’e is a largely unclothed human population. 
The ground is for long periods^ of the year covered deeply with a layer 
of dry dust or sand both in and out of dwellings. 
1 See footnote p. 48. 
4—2 
