1832.] SWARM OF ANTS. 2$ 



similar to that produced by a toothed wheel passing under a spring 

 catch. The noise was continued at short intervals, and could be dis- 

 tinguished at about twenty yards' distance : I am certain there is no 

 error in the observation. 



I was disappointed in the general aspect of the Coleoptera. The 

 number of minute and obscurely-coloured beetles is exceedingly great.* 

 The cabinets of Europe can, as yet, boast only ot the larger species 

 from tropical climates. It is sufficient to disturb the composure of an 

 entomologist's mind, to look forward to the future dimensions of a 

 complete catalogue. The carnivorous beetles, or Carabidse, 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 Harpalidae 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 Brachelytera 

 are very uncommon ; on the other hand, the Rhyncophora and 

 Chrysomelidae, 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 Orthoptera 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 migrates in countless numbers. 

 One day, at Bahia, my attention was drawn by observing many 

 spiders, cock-roaches, 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 files 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 impres- 



* I may mention, as a common instance of one day's (June 23rd) collect- 

 ing, when I was not attending particularly to the Coleoptera, that I caught 

 sixty-eight species of that order. Among these, there were only two of the 

 Carabidae, four Brachelytra, fifteen Rhyncophora, and fourteen of the Chry- 

 somelidse. Thirty-seven species of Arachnidae, which I brought home, will 

 be sufficient to prove that I was not paying overmuch attention to the gene- 

 rally favoured order of Coleoptera, 



