ZOOLOGY 195 
a mystery. In some instances, however, they appear to be in search of food and 
in others to be migrating. Their nests are believed to be in huge excavations 
near the roots of large trees. Sometimes the route, worn bare of vegetation by 
the passage of a long column of these ants, can be traced after it has passed. In 
some instances the column of insects, when crossing a trail or road, passes in a 
sort of depressed channel, the edges of which are lined with the soldiers, while 
the workers hurry along in the center. In other instances shallow tunnels or 
arches are constructed, under which the column passes. As is well known, these 
ants will invade a camp, a house or a village during the night and devour every 
edible thing within reach, including small animals such as rats, mice, cockroaches, 
lizards, and even poultry or other birds that are confined and cannot escape, and 
leave nothing behind them except clean-picked bones. Their method of attack 
on a moving animal, as, for example, a lizard, is very interesting. A large colunm 
of them will rush at the animal and then suddenly the whole band, those on the 
animal and those on the ground, will cling together and form a solid mass the 
weight of which the animal cannot drag and under which he cannot move. In 
a few seconds he is completely covered by a thick mass of ants and very soon 
entirely devoured. 
There is little doubt that a human being, particularly a child, if caught 
by the ants when held a prisoner, and unable to move, would soon be devoured 
by them. Johnston states that it has been a common outlet for African cruelty 
to peg down men, women, or children across the path of the driver ants, to die 
a horrible and lingering death, and that he has seen in several parts of Africa, 
the corpses of negroes who have been killed in battle or have died of disease, 
half eaten by these ants. Not far from one of our base camps the hut of a 
rubber planter was invaded one night by these insects. The planter had been 
an amateur collector of a number of birds and small animals, some of which 
were also in his room. Most of these were devoured during the night. Through- 
out the night the man himself crouched upon a table the legs of which he had 
placed in vessels containing kerosene. Once driver ants started to invade our 
camp, coming apparently in billions over the stockade and through the crevices 
of the fence around the camp and forming very numerous columns along a front 
of from thirty-five to forty feet wide. We were able to turn the attack of 
this enormous army into a complete rout and hasty retreat by spreading a 
thick layer of petroleum on the ground along the front of the advancing col- 
umns. It was very interesting to observe the universal, quick retreat. Within 
fifteen minutes there was not an ant to be seen in the compound. Biittikofer ! 
suggested that the remarkable scarcity of many types of insects and smaller 
pests and birds in Liberia might be due to the excessive numbers of both of 
the predatory driver ants, genus Anomma, and of the red tree ants, Oecophylla. 
The red tree ants are not so numerous as the driver ants and not so aggressive. 
Generally, they do not go very far from the trees in which they dwell but their 
bite is disagreeable and painful — all the more on account of the formic acid 
it leaves in the wound. They often make their nests in large leaves, which 
1 Bittikofer: ‘‘Reisebilder aus Liberia.”’ Leyden (1890). 
