xxv TICKS 



39 



these pests because the native hovs 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 da\ >. 

 When the jigger 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 larvaB 

 climb neighbouring plants and grass and fasten 011 

 passing animals. They remain on the animal for a few 

 days and after distending themselves with blood drop 

 oft', seek a place of concealment, and become torpid. At 

 the end of eleven weeks the nymph emerges, fastens on 



