E.
ANEURIN
LEWIS
389
HABITS AND LIFE- HISTORIES
The adaptability of many of the East African ticks to different classes
and species of hosts is astonishing. Only a few illustrations can be given
here, but they show how the ticks can adopt a variety of hosts and thus keep
up the infestation of a locality. A. marmoreum feeds readily on snakes,
tortoises, lizards, rhinoceros, buffalo, and more rarely on the other large
mammals and cattle. R. appendiculatus occurs commonly on horses, dogs,
all game animals, goats, sheep, and cattle. R. sanguineus may be found on
birds, hares, ant-bears, dogs, lions, on a few antelope, and on stock. R.
simus prefers rodents and other small animals as hosts for larvae, but, as nym¬
phae and adults, it infests dogs, birds, horses, pigs, goats, sheep, cattle, and
numerous species of game and vermin. Larvae of Ixodes, Hyalomma, and
Amblyomma are frequently taken off small birds, ground fowl, and hares,
whereas the nymphae and adults are found on many bush game and wild
animals in the high country and on the plains.
Most of the important species of ticks oviposit and moult on the ground
in the tufted masses of grass, at the base of bushes, and in niches or hollows
made in loose earth or sand. There are a few, like H. leachi, which prefer the
debris and rubbish around a dog's kennel for development ; or like Argas
persicus, which hides itself in cracks or fissures in the ground or among timber
and under any structure that provides dark shelter. H. leachi may penetrate
into rats' nests deep in the ground, where specimens in all stages of develop-
ment have been collected. R. sanguineus behaves very differently in houses.
The replete tick drops off a dog and often crawls up walls to seek shelter in the
framework of wooden houses, behind cornices or immediately above the
ceilings. The female lays her eggs in these situations, and engorged larvae and
nymphae moult there. The writer has seen, several times, numerous ticks
emerging from these hiding-places, spreading over the walls of a living-room
or forming a live column marching, as it were, directly towards a corner where
the housedog habitually rests and sleeps. In the case of Hyalomma species,
the adults are extremely active. When a person or an animal rests on the
ground in infested areas, the ticks can often be seen hurrying from all directions
to the likely host. It is interesting, too, to watch R. pulchellus adults poised
on blades of grass ready to cling to an animal that passes within range of its
extended fore-legs ; or to observe a brown cluster of larvae at the tips of grasses.
The life-histories are of the three-host type in the majority of ticks be-
longing to Rhipicephalus, Amblyomma, Haemaphysalis, Ixodes, and Aponomma.
A larva which hatches from an egg gains access to a host, feeds to repletion
drops to the ground and moults. The nympha which emerges from the moult
seeks another animal on which to feed. When engorged with blood, it leaves
the animal, drops to the ground, where it moults to produce an adult. The
male or female adult must now find a third host. The female will swell out
with blood and then drop off to lay her eggs and die. The male may remain
on the animal for several weeks ; he will feed more than once, but will not dis-
tend like the female.
B. annulatus decoloratus is a one-host tick. The larva feeds on a beast,
moults after engorging and, as a nympha, attaches once again near the original
spot. When the nympha is replete with blood, it casts its skin as the larva did,