3140 THE JOINTED ANIMALS 



resemble the nymphs of the perfect insects, are known as substitution kings and 

 queens, and take the place of true royal couples, when from any cause the latter are 

 not to be found. 



The food of white ants consists ordinarily of decaying wood, or similar vegtea- 

 ble matter, which, when it has passed in a half -digested state through their bodies, 

 is eaten again. These insects have also the habit of devouring their dead, which 

 makes it possible to destroy a whole colony by placing a little arsenic or mercuric 

 chloride in their food; for the few that die through first partaking of the poison 

 are eaten by others, which in their turn are also devoured, and so the poison is 

 spread through the entire population. About two hundred species of termites have 

 been described; and these inhabit -chiefly the tropical and subtropical parts of the 

 world, although two small species are found in the south of Europe. Some species 

 live in the hollows they have eaten out in the interior of the trunks and branches of 

 trees, or in timber. They line the galleries they make, which are often so close 

 together as to be separated only by a thin wall, the wood in the interior being almost 

 all eaten away. A few make openings to the exterior, and form nests around the 

 branches of trees; these nests being sometimes as large as a sugar barrel, though 

 the size varies considerably. The nests of most species are usually placed entirely 

 below the level of the ground, and often lie beneath mounds of earth raised above 

 the surface. Some of the larger African species, such as Termes bellicosus, build 

 mounds of earth, frequently reaching a height of twelve or fourteen feet. These 

 mounds, which may stand singly, or in groups of varying size, are divided inside 

 into chambers and galleries communicating with one another and with the nests and 

 galleries underground. The nests of this kind, which consist almost entirely of 

 clay, become in time quite hard and solid, and are much more durable than those 

 -which are composed of particles of dead wood pasted together with a sticky saliva 

 or with excrementitious matter. From the central nests termites construct under- 

 ground galleries or tunnels leading in different directions, and sometimes reaching 

 hundreds of feet in length. When it is necessary for the workers to go above 

 ground in search of food, they protect themselves by building covered ways 

 leading to the object they desire. Their tunnels sometimes lead to the interior 

 of houses, and when once termites gain admittance in this way there is scarcely any 

 limit to the mischief which may result from their operations. The wooden pillars 

 that support the roof, the woodwork of the roof itself, and even articles of furni- 

 ture, may be destroyed before the inhabitants become aware of what is taking place. 

 For in tunneling through wood termites take care to leave the outer shell intact; 

 and what appears on the outside to be a solid piece of wood may consist in the 

 interior of nothing but a series of galleries lined with white-ant mortar. These 

 insects easily make their way into wooden boxes, and quickly destroy the books, 

 papers, clothing, or whatever else they may contain. The rapidity with which they 

 work is remarkable, and in a single night they have been known to burrow up through 

 the leg of a table, then across the table, stopping on the way to devour the articles lying 

 on it, and down through another leg into the floor again. Forest trees, also, are often 

 ruined by the action of termites, which, in order to get at the dead branches will some- 

 times bore their way up through the trunk, and thus bring about its premature decay. 



