DETERRENT TREES AND PLANTS. 25 



four females of Culex pipiens. They wished to see if the instinct 

 which attracts the mosquitoes toward the light and toward an appar- 

 ent way of escaping, and on the other hand the need of nourishment 

 and water, would induce the mosquitoes to pass the middle portion 

 of the bar which was entirely filled with large leaves of the pawpaw. 

 At the end of four minutes one Anopheles and one Culex had passed 

 from one end of the bar to the other: at the end of ten minutes another 

 Anopheles and two Culex were seen to place themselves upon the 

 pawpaw leaves and they remained there for hours. The mosquito 

 bar was left intact for eight days. During this period the mosquitoes 

 went everywhere and rested sometimes several hours upon the leaves 

 and upon the branches. 



An experiment exactly similar was carried on at the same time 

 with Ricinus communis, with precisely similar results. When these 

 experiments concluded at the end of eight days one Anopheles and 

 one Culex were found dead in the pawpaw mosquito bar. and in the 

 Ricinus bar also one Anopheles and one Culex. But in similar eages 

 in another room during the same time six Anopheles out of twenty 

 had died and nine Culex out of twenty-eight, in the absence of the 

 Carica and Ricinus plants. The authors concluded that pawpaw, 

 castor-oil plant, and eucalyptus are powerless in their effect on 

 mosquitoes. 



CHINABERRY TREES. 



In spite of the statement that chinaherry trees will protect against 

 mosquitoes, observations have failed to show the truth of the state- 

 ment, and in mosquito regions people are quite as liable to be bitten 

 while sitting under a chinaherry tree as under any other tree. Never- 

 theless there is an observation upon record which suggests that further 

 experiments will be interesting. In the Public Health Reports, Vol. 

 21, No. 44, November 1, 1901, Dr. G. M. Corput, assistant surgeon, 

 U. S. Marine-Hospital Service, gave the results of certain experiments 

 conducted by hanging cans of water in the branches of different trees, 

 including oak, pine, cherry, and palmetto. He found that in the 

 can hung in the chinaherry bushes there were no mosquito larvae at 

 any time, although larva 1 were found in all of the other cans. 



OTHER PLANTS. 



A number of plants credited with being deterrent to mosquitoes 



have been mentioned from lime t»> time in the newspapers, some o{ 

 the account-- being of a sensational character. The New York 

 papers, for example, in the summer of 1906 contained numerous 

 notices of the so-called "phu-lo" plant introduced from the Tonkin 

 country in French [ndo-China by Baron de Taillac. This plant was 

 said to he valuable as a Fodder for cattle, and to drive away mosqui- 



