XXV 
TICKS 
309 
these pests because the native boys employed as 
domestic servants often have jiggers in their feet. 
When the eggs in the flea mature they are expelled and 
fall to the ground ; as these boys run about with bare 
feet the dust on the floor of the house soon swarms with 
fleas; if the white people living in the house walk about 
their rooms with bare feet they very quickly get infected, 
especially babies. The floors of rooms should also be 
kept as free as possible from dust, as this harbours the 
fleas. 
The life-history of the sand flea is briefly this :— 
The unimpregnated female jigger, like the male, is 
free : when impregnated she avails herself of a warm¬ 
blooded animal, burrows into the skin, and proceeds to 
grow eggs. As the eggs ripen the flea attains the size 
of a small pea. When the eggs (ova) are mature they 
are expelled and fall on the ground and a larva hatches 
out of each : this larva spins a cocoon for itself and 
emerges as a perfect sand flea in eight or ten days. 
When the j igger is retained in the skin until the eggs 
are laid, the skin ulcerates and the flea is expelled. 
This leaves an uncomfortable ulcer. 
Ticks belong to the same group of Arachnids 
as mites. The ticks are blood-sucking parasites 
which attack animals, wild and domesticated, and 
man : they are nearly always acquired from vegetables, 
grass, and herbage. 
The life-history of a tick ' is briefly this:—A female 
tick attaches herself to an animal for a time, and then 
drops off and lays eggs, which are small, yellow 
grains, like roe, in the soil ; as many as ten or even 
twenty thousand may be laid by one tick. The eggs 
take from three to five weeks to hatch and the larvse 
climb neighbouring plants and grass and fasten on 
passing animals. They remain on the animal for a few 
days and after distending themselves with blood drop 
off, seek a place of concealment, and become torpid. At 
the end of eleven weeks the nymph emerges, fastens on 
