Food of a sort may often be had for the plucking, and raiment is needless; but aside from the menace of the elements human life is endangered by beasts and reptiles in the forest, crocodiles and hippopotami in the rivers, and sharks in the sea, and existence is made a burden to all but the happy-hearted by plagues of insects and parasites.

In many districts tse-tse flies exterminate the cattle and spread the fatal sleeping-sickness among men; everywhere swarms of locusts occasionally destroy the crops; white ants eat timbers and any other useful thing, short of metal, which may come in their way; giant cockroaches and dwarf brown ants and other pests in great variety swarm in the dwellings continuously--except just after a village has been raided by the great black ants which are appropriately known as "drivers." These drivers march in solid columns miles on miles until, when they reach food resources to their fancy, they deploy for action and take things with a rush.

To stay among them is to die; but no human being stays.

A cry of "Drivers!" will depopulate a village instantly, and a missionary who at one moment has been combing brown ants from his hair will in the next find himself standing safely in the creek or the water barrel, to stay until the drivers have taken their leave.

Among less spectacular things, mosquitoes fly in crowds and leave fevers in their wake, gnats and flies are always on hand, chigoes bore and breed under toe-nails, hook-worms hang themselves to the walls of the intestines, and other threadlike worms enter the eyeballs and the flesh of the body.