TROPICAL INSECTS. 581 



ANIMALS OF THE TROPICAL WORLD. 



CHAPTER VIII. 



INSECTS. 



Multitude of Tropical Insects— Beetles — Dragon Flies — Leaf Moths — The Leaf Butterfly — 

 Fire Flies — Insect Plagues: Mosquitoes — Chigoes, or Jiggers — The Filaria Medinensis — 

 The Bete Kouge— Ticks— Land-Leeches— The Tsetse Fly— The Tsalt-Salya Locusts- 

 Cockroaches — Enemies of the Cockroach. — Useful Insects: The Silk- Worm — The Cochineal 

 Insect — The Gum-Lac Insect — Edible and Ornamental Beetles. 



HAVING thus passed in rapid survey over the characteristic forms of the Vege- 

 table World of the Tropics, we now proceed to the Animal Kingdom, com- 

 mencing with Insects, and proceeding to Reptiles, Birds and Beasts. 



On advancing from the temperate regions to the pole, we find that insect life 

 gradually diminishes in the same ratio as vegetable life declines. The reverse takes 

 place on advancing towards the equator ; for, as the sun rises more and more to the 

 zenith, we find the insects gradually increasing with the multiplicity of plants, and at 

 length attaining the greatest variety of form, and the highest development of number, 

 in those tropical lands where moisture combines with heat in covering the ground with 

 a dense and everlasting vegetation. Thus while not a single species of beetle is found 

 on Melville Island, Greenland boasts of 11 ; Lapland of 813; Sweden of 2,083. In 

 the milder climate of England their number increases to 2,263 ; in France it rises to 

 4,200; and the hothouse temperature of Brazil, from Bio Janeiro to Bahia, fosters no 

 le.ss than 7,500 specific forms of beetle life. In Borneo Mr. Wallace collected 2,000 

 distinct species of beetles within the space of a single square mile; some of them of 

 forms to the oddity of which no parallel can be found elsewhere. Thus, also, while 

 the whole of Europe and Siberia hardly possess more than 250 butterflies, the ex- 

 plored parts of Brazil, which are very inferior in extent, have already furnished the 

 naturalist with no less than 600 species, and no doubt contain many more. 



In the countries which, from the never failing abundance of food, and constant 

 warmth, are most favorable to the multiplication of insects, these creatures may 

 naturally be expected to attain the greatest size. Thus the European rhinoceros 

 beetle, though an inch and a quarter long, is far surpassed by the Megasominac 

 of torrid America. The colossal Hercules beetle attains a length of five or even six 

 inches, and is distinguished, like the other species of the genus, by the singular horn- 

 shaped processes lising from the head and thorax, which give it a very grotesque and 

 even formidable appearance. Though but little is yet known of its economy, it most 

 likely subsists upon putrescent wood, and evidently leads a tree life, like the other 



U 



