98 TEOPICAL NATURE, AND OTHER ESSAYS. 



canoes, and will even ensconce themselves under pillows 

 and in beds, rendering a thorongli examination necessary 

 before retiring to rest. Yet with moderate precautions 

 there is little danger from these disgusting insects, as 

 may be judged by the fact that during twelve years 

 wanderings in American and Malayan forests the author 

 was never once bitten or stung by them. 



General Observations on Tropical Insects. — The 

 characteristics of tropical insects that will most attract 

 the ordinary traveller, are, their great numbers, and the 

 large size and brilliant colours often met with. But a 

 more extended observation leads to the conclusion that 

 the average of size is probably no greater in tropical 

 than in temperate zones, and that, to make up for a 

 certain proportion of very large, there is a corresponding 

 increase in the numbers of very small species. The 

 much greater size reached by many tropical insects is no 

 doubt due to the fact, that the supply of food is always 

 in excess of their demands in the larva state, while 

 there is no check from the ever-recurring cold of winter ; 

 and they are thus able to acquire the dimensions that 

 may be on the whole most advantageous to the race, 

 unchecked by the annual or periodical scarcities which in 

 less favoured climates would continually threaten their 

 extinction. The colours of tropical insects are, probably, 

 on the average more brilliant than those of temperate 

 countries, and some of the causes which may have led 

 to this have been discussed in another part of this 

 volume.^ It is in the tropics that we find most largely 

 developed, whole groups of insects which are unpalatable 

 to almost all insectivorous creatures, and it is among these 



^ Chapters V. and VI. — The Colours of Animals and Plants. 



