63 



trees. My irrigating ditch, a dozen feet wide, of sluggish current, runs through the 

 grove beside the house. There has never a single mosquito larva been seen in the 

 ditch from where it enters the first shade of these trees to where it emerges from them 

 200 yards away, while above and below mosquito larvse are plentiful — not imme- 

 diately below, but some hundreds of yards away, where the water stands in pools 

 and becomes stagnant among a growth of black walnuts and cottonwoods. 



My live stock pasture in this timber, going into the walnuts and back again under 

 the eucalyptus shade at pleasure. Frequently when the cows come up at night they 

 bring a swarm of mosquitoes; occasionally some of them get into the house, but 

 cause us so little annoyance that we scarcely notice them. Before this ditch reaches 

 the Eucalypti it runs through a jungle of "fence bamboo" {Arundo macrophylla) , 

 where the mosquitoes are so bad that we avoid working there except on the windiest 

 days. And, though the ditch has more current there, the larv£e of mosquitoes are 

 plentiful in the water till it reaches the Eucalyptus trees, below which point none 

 are found till it has become stagnant away below them. 



People who have camped along the willows of Kings River, only a few miles 

 away, have come here with faces so blotched and swollen from mosquito bites as to 

 be hardly recognizable, and have camped in the shadeof "Sanders's gum trees," as 

 my grove is popularly called, for weeks, and declare that they never even heard a 

 mosquito sing during that time. 



To the non-botanical reader I may say that this species of Eucalyptus is very tender 

 to frost. The coldest weather ever known here, 19° F. above zero, killed thousands 

 of them. 



Dr. Nuttall points out that the planting of eucalyptus trees is not a 

 sovereign remedy, from the fact that malaria still prevails at Tre 

 Fontane, outside of Rome, in spite of Eucalyptus plantings. The 

 mere planting of trees, however, is undoubtedly of use in malarial 

 districts, since it will modify the condition of drainage of the soil. 

 In view of Mr. Sanders's strong evidence it really appears that plant- 

 ing of eucalyptus trees will be worth while in certain locations, not 

 entirely (on account of the conflicting and not thoroughly satisfactory 

 evidence) for mosquito protection, but incidentally for this use a.s well 

 as other purposes. 



DRAINAGE AND COMMUNITY WORK. 



After all, the best of the means which may be adopted against mos- 

 quitoes will always consist in the abolition of their breeding places. 

 Small pools with stagnant water can be treated, but it is a great deal 

 better to drain them or to fill them up. Swamp areas must sooner or 

 later be drained. It is perfectly obvious that the sooner this is done 

 the better from every point of view, not only from that of human 

 health but from the increased value of real estate in the neighborhood 

 and from the practical value of the reclaimed land itself. The time is 

 coming, and rapidly, when this drainage of large swamps will not 

 remain a matter which concerns the individual owner of the land, but 

 one for town or county action, and even for States. The report of 

 T. J. Gardner on the policy of the State respecting drainage of large 

 swamps, published in the Report of the Board of Health for New York, 



