DETERKENT TREES AND PLANTS. 23 



reached a height of 140 feet. According to his statement, an irrigat- 

 ing ditch ran through the grove, but there was never a single mos- 

 quito larva in the grove, although on both sides of the grove larvae 

 were plentiful. On the other hand, the late Dr. A. Duges, of Guana- 

 juato, Mexico, wrote the Chief of the Bureau, on September 8, 1900: 



I have received your very interest ing study of the mosquitoes of the United States 

 and thauk you greatly for it. At the end of the book you speak of the utility of euca- 

 lyptus for driving away insects. I have had some experience with these trees. The 

 fresh leaves placed upon the pillow will attract mosquitoes. Thinking that the 

 mosquitoes loved this plant I had placed the branches farther away, but without result. 

 I have burned the leaves in my chamber, and the cursed beasts have resisted the 

 smoke. 



Eucalyptus trees of many species are now grown generally all 

 through California, and the idea that they drive away mosquitoes 

 must be abandoned. Mr. H. J. Quayle, in Bulletin 178 of the Califor- 

 nia Agricultural Experiment Station, states that in the Burlingame 

 section not far from San Francisco, all of the avenues are lined with 

 eucalyptus trees and mosquitoes are most numerous where these 

 trees are most abundant. In 1901 he captured a pint cup of mos- 

 quitoes immediately under eucalyptus trees. Coyote Point is covered 

 with eucalyptus trees, yet the construction of a hotel on the point 

 was abandoned on account of the abundance of mosquitoes. 



Edmond and Etienne Sergent, in their antimalarial work in Algeria, 

 had occasion to study the question of eucalyptus and published their 

 results, together with the results of their observations and experi- 

 ments upon certain other plants supposed to be deterrent to mosqui- 

 toes, in the Comptes Rendus des Seances de la Societe de Biologie, 

 November 14, 1903. With regard to eucalyptus they show that the 

 railway station of Ouled-lvahmoun, formerly greatly troubled by 

 mosquitoes, was visited by them much less frequently after the cutting 

 down of great eucalyptus trees which surrounded it. The station of 

 Ighzer-Amokran, which is isolated in the middle of a desert plain, is 

 surrounded by a little grove of eucalyptus. Before the windows and 

 doors were screened the rooms were visited every evening by quan- 

 tities of Anopheles. The traveling Kabyles who stopped at this sta- 

 tion would never sleep at midday under the foliage of the eucalyptus. 

 for they said mosquitoes always came down on them. They went 

 under the olives, where they were never bitten. 



CASTOR-OIL PLANT. 



During the winter of 1901 a great deal was said in the newspapers 

 about the planting of the castor-oil plants (Ricinus communis) to pre- 

 vent mosquitoes. These notes at that time were mainly based upon 

 a consular report from Capt. E. II. Plumacher, United States consul 

 at Maracaibo, Venezuela. In this report Captain Plumacher stated 



