THE DOMINANT INSECT 9 



mosquitoes, the intrepid arctic explorers of the insect 

 world, have passed the seventy-second line of north 

 latitude. A small species of butterfly was captured on 

 a mountain in Ecuador 10.500 feet above sea-level. 

 There are desert insects dwelling where no water is, 

 while others have penetrated the very bowels of the earth, 

 for the subterranean galleries and chambers of limestone 

 districts have an insect population all their own. Several 

 kinds are known to inhabit the cavern of Mitchelstown in 

 the south of Ireland, while dozens of species, including 

 crickets and beetles, have been found within the vast 

 caves of Carniola in Austria and of Kentucky in North 

 America. Certain of these insects seem to have strayed 

 underground quite recently, for they differ little in appear- 

 ance from their relatives which enjoy the sunlight and 

 free air. But others are the lineal descendants of ancestors 

 which espoused a subterranean life countless centuries 

 ago. These hereditary cave-dwellers are pale and wan, 

 like captive exiles of a Siberian mine. All of them are 

 blind. Indeed, diligent dissection beneath the microscope 

 often fails to reveal any trace of the eye or of the optic 

 tracts of the brain. Possibly the sense of touch alone 

 remains with these strange insects. Yet they pass their 

 lives in well-ordered activity. The lesser eat the red 

 earth which covers the floors of their galleries, subsisting 

 upon the minute particles of vegetable matter which it 

 contains — the fragmental decay of fungi which grow 

 within the caves, or of other plants carried there by sub- 

 terranean streams. Upon the lesser the larger species 

 prey. Thus the old drama of life is enacted in these 

 silent caverns, far from the light of day. 



Many insects have likewise invaded the fresh waters 

 of the globe, and these exhibit remarkable modifications 

 which fit them for an aquatic life. In a subsequent 



