XX XIX 



" The carnivorous beetles, or CarahuJce, appear in extremely 

 few numbers within the tropics : this is the more remarkable 

 when compared to the case of the carnivorous quadrupeds, 

 which are so abundant in hot countries. I was struck with this 

 observation both on entering Brazil, and when I saw the many 

 elegant and active forms of the HarpaUda re-appearing on the 

 temperate plains of La Plata. Do the very numerous spiders 

 and rapacious Hymenoptera supply the place of the carnivorous 

 beetles '? The carrion-feeders and BracJielytra are very un- 

 common ; on the other hand, the Rhynchophora and Chrijso- 

 vielidce, all of which depend on the vegetable world for sub- 

 sistence, are present in astonishing numbers. I do not here refer 

 to the number of different species, but to that of the individual 

 insects ; for on this it is that the most striking character in the 

 entomology of different countries depends. The orders Ortho- 

 ptera and Hemiptera are particularly numerous ; as likewise is 

 the stinging division of the Hymenoptera ; the bees, perhaps, 

 being excepted. A person, on first entering a tropical forest, is 

 astonished at the labours of the ants ; well- beaten paths branch 

 off in every direction, on which an army of never-failing 

 foragers may be seen, some going forth and others returning, 

 burdened with pieces of green leaf, often larger than their own 

 bodies. 



" A small dark-coloured ant sometimes emigrates in countless 

 numbers. One day, at Bahia, my attention was drawn by 

 observing many spiders, cockroaches, and other insects, and 

 some lizards, rushing in the greatest agitation across a bare 

 piece of ground. A little way behind, every stalk and leaf was 

 blackened by a- small ant. The swarm having crossed the bare 

 space, divided itself, and descended an old wall. By this means 

 many insects were fairly enclosed ; and the efforts which the 

 poor little creatures made to extricate themselves from such a 

 death were wonderful. When the ants came to the road they 

 changed their course, and in narrow tiles re-ascended the wall. 

 Having placed a small stone so as to intercept one of the lines, 

 the whole body attacked it, and then immediately retired. 

 Shortly afterwards another body came to the charge, and again, 

 having failed to make any impression, this line of march was 

 entirely given up. By going an inch round, the file might have 

 avoided the stone, and this doubtless would have happened, if it 



