CHAPTER V. 



HYDRADEFHAGA, OR PREDACIOUS WATER BEETLES. 



CoNSiDEKiNG the vast wealth of insect life which is seen in the 

 hotter countries of the world, we might readily imagine that 

 under a ti-opical sun every group of insects must be developed to 

 the fullest extent. 



The practical entomologist, howe\'cr, knows that this is not 

 the case. Some groups — such, for example, as the Long-horned 

 Beetles and the Ants — swarm in such vast numbers that the 

 insect-hunter finds almost every rood of ground add to his 

 collection numbers of species hitherto unknown to science. 

 And, if another collector should go over the same ground, the 

 latter is nearly certain to find many species M^hich his pre- 

 decessor had missed, i^artly on account of the different mode of 

 working which any two practical men must needs adopt, and 

 partly because the numbers of the insects are so enormous that 

 it is hardly possible for one individual to exhaust the resources 

 of a single district, however carefully he may ransack it. 



But, though some groups are so enormously strong in numbers, 

 others are strangely deficient, sadly disappointing the ento- 

 mologist, who thinks that he may add to the present stock of 

 insect lore, information concerning numbers of species which he 

 hopes to discover. Such a group is that which forms the sub- 

 ject of the present chapter. In this country, where the hottest 

 summer heats are barely the average of a tropical temperature, 

 where the thermometer often indicates a frost below zero, and 

 where for months together the earth is often covered with snow 

 and the water with a thick coating of ice, the Water Beetles 

 thrive wonderfully. They are marvellously hardy beings, revel- 

 ling in the full blaze of the summer sun, and yet darting about 

 in the depth of winter, apparently quite as contented with the 



