384
The Ticks of East Africa
R. pulchellus (the zebra tick) thrives best on the plains, in Acacia-desert
grass and Acacia-tall grass savannahs east of the Rift Valley in Kenya. It is
more rarely found in the Rift and to the west of the Valley in the Colony, but
occurs in Tanganyika and in Uganda. The tick is normally absent from dis-
tricts higher than 6,600 ft. above sea-level and may be said to be a species of
the lower highlands and, to a less extent, of the coastal zone. In the higher
altitudes it prevails in the open or semi-open, dry and hot areas, but it cont-
rives to maintain itself in the hot and less humid regions near the sea and the
inland lakes. It seems to be fairly resistant to short periods of cold. R.
maculatus is more of a lowland tick than R. pulchellus and is confined to country
below 4,000 ft. It has not yet been found in the colder, moist highlands.
B. annulatus decoloratus is pre-eminently a species of the moist regions, pre-
fers the high plateaux, and is abundant in the cold districts of Kenya Colony
where dipping has not eradicated it. The tick flourishes also in the highland
forests and glades, but is seldom found in the open dry areas, such as on the
plains of the Masai Reserve, the Yatta plateau, the semi-arid areas of Ukamba,
and the more extensive scrub areas of the Northern Frontier Province. On
the other hand, it abounds in the wooded areas of the Mau hills, in the high
(8,000 ft.) country of Limuru ; and, in fact, throughout the European high-
lands. Mettam [1932] records it from Uganda and the writer has received
numerous specimens from that Protectorate and from Mpwapwa, which is
relatively low (3,500 ft.) but sheltered by wooded hills. Its wide range in
Kenya, from the coast to Lake Victoria Nyanza, indicates the adaptability
of the species and its resistance to heat and cold, provided moisture is avail-
able.
The species and sub-species of Hyalomma find the conditions of the arid
and desert areas most suitable. They occur most abundantly in the lower dry
and sandy districts. H. planum is common in the Rift Valley, in the scrub¬
forest areas of Kitui district, and in the hinterland of the coastal zone. H.
anatolicum and H. dromedarii are chiefly species of the Northern Frontier Pro-
vince, but, as will be noted later, they have penetrated farther south in Kenya,
in Uganda, and in Tanganyika. The other species are less frequently found ;
and are scattered in very small numbers even in the highlands. H. leachi,
the common dog-tick, is widespread. It occurs in all districts and at different
altitudes. Yet, from numerous field observations, it seems to prefer the shel-
ter of dense scrub and grassy woodlands as so many other species do. It
has frequently been collected from the lairs of wild animals, in nesting places
and houses of animals—more especially of the canine and feline tribes. R.
sanguineus, commonly known as the dog brown-tick, is not so abundant as
H. leachi. It is a species of the more densely populated European areas. Its
range of hosts, however, is equal to, if not greater than, that of H. leachi.
Adults, nymphae, and larvae have been taken off lion, jackal, cheetah, and the
different antelopes on the plains of the Masai Reserve, the Northern Frontier
Province, and in European areas. It has often been found in the Coast areas,
in forests, in deserts, and in towns ; it has been collected from a variety of
birds, large wild game, and off cattle. The tick has been observed to infest
dogs heavily in townships and on farms ; but the writer has never found the
tick in native huts where dogs rest and sleep more or less with the family.