216 MOSQUITOES 



blue gum occurs no other remedy need be sought for. 

 Further than that, he stated that no matter how plentiful 

 the mosquitoes are, a few twigs or leaves laid on the pil- 

 low at night will secure perfect immunity. The same year, 

 Mr. W. A. Sanders, of California, wrote that he had planted 

 eucalyptus trees nineteen years previously about his 

 house and that they had reached, some of them, a height 

 of 140 feet. An irrigating ditch ran through the grove, 

 but there was never a single mosquito larva in the ditch 

 in the grove, although on both sides of the grove larv?e 

 were plentiful. In the grove, mosquitoes were never 

 found, though outside they were plentiful. This seems 

 very strong evidence, but there is also evidence to show 

 that eucalyptus trees are not at all effective. Dr. Alfredo 

 Duges, the well known naturalist of Guanajuato, Mexico, 

 wrote me on September 8, 1900 : " I have received your 

 very interesting study of the mosquitoes of the United 

 States, and thank you greatlj^ for it. At the end of the 

 book you speak of the utility of eucalyptus 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 have placed the branches farther away, but 

 without result. I have burned the leaves in my chamber, 

 and the cursed beasts have resisted the smoke." Dr. 

 Nuttall states that malaria still prevails in certain local- 

 ities outside of Rome, in spite of eucalyptus plantings. 



