XXVI INSECTA : HYMENOPTERA 423 



place, sheltering under stones, in crevices in rocks or in the 

 soil. They dislike light, and travel at night or on a cloudy- 

 day. If overtaken by sunlight when no shelter is at hand, 

 they construct tunnels of mud, made to adhere by mixing it 

 vi^ith saliva, and they move onwards sheltered by these. 

 They feed on any desirable animal food they overtake on their 

 raids, killing animals many times their own size. Moreover, 

 they enter any promising house they come across, and drive 

 before them all the various uninvited inmates of the house, 

 such as mice, cockroaches, lizards, etc., eating all they fancy, 

 whether it be any of these vermin, or any meat that they 

 may find. Their invasions may clear a house of vermin, but 

 it is not an altogether welcome invasion to the rightful 

 owners, who appear to be driven at times to sitting on 

 their beds, with the feet of the bedsteads in basins of 

 vinegar to isolate them until their uninvited guests have 

 come and gone ! It is a curious fact that, although they live 

 so much above ground, the workers of these ants are totally 

 blind, and they find their way only by the " contact-odour " 

 sense of the antennae (see p. 414). The workers vary 

 greatly in size, one set forming the " soldier caste " with 

 strong toothed mandibles, others being much smaller and with 

 small mandibles. They act in common, to a large extent, and 

 Savage describes how he watched a colony, which was camping 

 on a tree, form a rope of living ants, over which the others 

 passed up and down from the ground to the lower branches. 

 The rope was as thick as a man's thumb, and was formed from 

 above, the first ants climbing the tree-trunk, and then hanging 

 from a bough, whilst others passed over them and hung on 

 to their legs, and so on until the rope nearly reached the 

 ground, when the last ants caught hold of a leaf of a plant 

 on the ground, thus completing the ladder or bridge and 

 holding it firm. 



Another use of the habit of clustering together appears in 



times of flood, when the larger workers cluster in a ball, with 



the pupae, eggs, and other members of the colony in the centre, 



and float in the water until they reach some foothold of dryland. 



Most ant-nests in temperate regions consist 



of^est^ simply of galleries and chambers excavated in the 



earth, but, in the Tropics, nests are frequently found 



hanging from the branches of trees, looking, it is said, like 



