334 THE BOOK OF THE ANIMAL KINGDOM 



wantonly. The result was a marked and rapid increase in the 

 larvae of the Processional Moth, which latter had been hitherto for 

 the most part destroyed by t the Bats. From that time onwards 

 these insect pests increased to such a degree, that in the course 

 of the following years first all the oaks, and afterwards also many 

 other trees, for miles around, were exterminated." 



And what enemies has the Bat? It does not appear to possess 

 many, because of its being nocturnal and continually on the wing 

 when away from its hiding-place, and also by reason of the in- 

 accessibility of its retreat. Another member of the nocturnal police 

 force, the Owl, will pounce upon a Bat when on the wing, and it 

 is stated that the Marten, Polecat, Weasel, and Cat will do so 

 while it is at rest. A Dog, however, does not care to touch it. 

 In addition to their usefulness as insect-eaters, Bats are of service 

 to man and bring him considerable wealth where they congregate 

 in any large numbers, for, when such is the case, guano or excre- 

 ment is found in great quantity. 



This is especially so in the guano caves of San Antonio in 

 Texas, but the valuable excretion has also been located in other 

 countries such as Italy, France and the Pyrenees. It will naturally 

 be concluded that to be found in a marketable quantity a tremendous 

 number of Bats must be congregated in the cave frequented, and 

 we are told that the number of animals in the largest cave is 

 enormous. Mr. Protheroe says that "when evening comes it is a 

 wonderful sight to see them issue forth from the mouth of the 

 cave in a dark stream, like a moving cloud, for quite two hours, 

 with a noise of whirring wings which sounds like a gale of wind. 

 The sight is wonderfully interesting, but the stench from the 

 creatures is almost unbearable. The supply of guano is naturally 

 not inexhaustible. When the guano has been taken from a cave 

 it is closed for a period of four years, by which time there is another 

 deposit well worth removal." 



There are more than four hundred and fifty different species of 

 Bats known to science, and probably many more remain to be 

 discovered. One, or at most two, young are produced during the 

 Summer. It would serve no good purpose in a popular work of 

 this description to set out reiterated details of a large number of 

 species, as they are more or less alike in their general characteristics, 

 and a few typical kinds need only be mentioned. Before coming 

 to these, however, it will be as well to state that, except in cold 



