EUCALYPTUS 413 
ALLEGED DETERRENT TREES AND PLANTS. 
There are many statements scattered through the literature that there are 
certain trees and plants in the neighborhood of which mosquitoes are never 
found. Notable among these are the Eucalyptus trees and the castor bean plant. 
Of recent years there have been many newspaper notes about other plants, and in 
the Southern States the chinaberry tree is said to be repellant. 
EUCALYPTUS. 
The statement has often been made that the planting of Hucalyptus trees in 
malarial regions will drive away malaria. This idea had become rather firmly 
grounded before the discovery of the carriage of malaria by mosquitoes. It has 
been said, for example, that the planting of Eucalyptus trees in the Roman 
Campagna was followed by a noted improvement in the malarial conditions. 
Eucalyptus oil has been used to keep mosquitoes from biting. Mr. Alvah A. 
Eaton, of California, wrote to the Bureau of Entomology, Department of Agri- 
culture, in 1893, that, in his opinion, where the blue gum grows no other remedy 
against mosquitoes need be sought for. He further stated that, no matter how 
plentiful mosquitoes may be, a few twigs or leaves laid on the pillow at night will 
secure immunity. Another correspondent of the Bureau, Mr. W. A. Sanders, 
wrote from California that he had planted Hucalyptus trees about his house 19 
years previously and that they had reached a height of 140 feet. According to 
his statement an irrigating ditch ran through the grove, but there was never a 
single mosquito larva in the grove, although on both sides of the grove larve 
were plentiful. On the other hand, Dr. A. Dugés, of Guanajuato, Mexico, wrote 
the Chief of the Bureau on September 8, 1900: 
“T have received your very interesting study of the mosquitoes of the United 
States and thank you greatly for it. At the end of the book you speak of the 
utility of Hucalyptus 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 further 
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 Cali- 
fornia, and the idea that they drive away mosquitoes must be abandoned. Mr. 
H. J. Quayle, in Bulletin 178 of the California Agricultural Experiment Sta- 
tion, states that in the Burlingame section, not far from San Francisco, all of the 
avenues are lined with Hucalyptus trees, and mosquitoes are most numerous 
where these trees are most abundant. In 1901 he captured a pint cup of mos- 
quitoes immediately under Hucalyptus 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 anti-malarial work in Algeria, had 
occasion to study the question of Hucalyptus, and published their results, to- 
gether with the results of their observations and experiments upon certain other 
plants supposed to be deterrent to mosquitoes, in the Comptes rendus des Séances 
de la Société de Biologie, November 14, 1903. With regard to Hucalyptus they 
