216 GNATS OK MOSQUITOES — CHAPTER VlII 



covered in all, and is in a number of instances already 

 known. The older frame of mind saved all trouble in 

 thinking, and therefore, quite unconsciously, the modern 

 standpoint is repugnant to them, and they resent being 

 told that if they plan their gardens so as to be perfect incu- 

 bators for Mosquitoes and refuse to adopt the most simple 

 precautions against being bitten, they have only themselves 

 to thank if they get fever. That though now and again the 

 insect may have been reared elsewhere, the chances are nine 

 to one that the gnat that inoculated them would never have 

 seen the light had not they themselves provided his parents 

 with every possible convenience for rearing their family. 



As a matter of fact, every naturalist would scout the 

 idea that we can hope to perceptibly diminish the number of 

 Mosquitoes in tropical regions ; and can probably advance 

 better grounds for the faith that is in him than those who 

 picture him as proposing to root out the race ; but he does 

 not share in popular notions as to these insects "appearing" 

 from no ascertainable origin, or that they can migrate or be 

 carried long distances by the wind. He knows on the contrary 

 that for all practical purposes every locality breeds its own 

 Mosquitoes, and that whenever he sees one of these insects 

 he may be sure that the water it was reared in is not a quarter 

 of a mile off. Given that a place be destitute of collections of 

 water suitable for rearing the larvae and it will be necessarily 

 free from Mosquitoes, even if there be places that swarm 

 with them within a mile's walk. From this it follows that to 

 secure a local immunity from them is almost always within 

 the range of possibility, and may in a few cases be a quite 

 simple matter, and resolves itself essentially into a question 

 of expense. Given that we have free access to the entire 

 area, and liberty to deal with every breeding pool we discover 

 as we think best, there are very few collections of water that 

 cannot be drained, filled in, or in some other way rendered 

 unfit for the rearing of Mosquito larva) ; but in many cases the 

 cost would be proliibitory, as for example where tlie insects 

 larvate in rice fields, and if we desire to prevent the nmltipli- 

 cation of Anopheles, we must make, up our minds to prohibit 

 the cultivation of the staple food of the population — too 



