62 



violent struggling evidently assisted in the breaking of the larval skin, 

 leaving the pupa bare. This transformation from larva to pupa is 

 hardh' as interesting as the rapid development of adults, 18 of whieh 

 issued within fifteen hours after transformation to pupa, whereas 

 previously the shortest duration of the pupal state which we had 

 observed was forty-eight hours. It looks like an effort of nature to 

 perpetuate the species in the presence of a unique emergency. 



On the whole, the result of the experiments with tar and tar oils was 

 rather unsatisfactor}^ as compared with the heavier grades of kerosene. 

 The effect of the tar was not permanent, and the effect of the creosote 

 oils was not as rapid as that of kerosene, and the writer is inclined to 

 the opinion that the heavier grades of kerosene oils are, on the whole, 

 preferable, although the effect of the creosote oils is very good, and 

 they can be used to advantage. He is inclined to think that they may 

 prove to be more permanent, although not quite so rapid in their 

 effect, than the lighter illuminating oils. 



EUCALYPTUS TREES. 



In addition to the use of eucalyptus oil on the skin to keep mosquitoes 

 from biting, the growth of eucalyptus trees is said by certain persons 

 to drive mosquitoes away, and trees of the genus Eucalyptus have 

 been especially recommended for planting in malarial regions. Mr. 

 Alvah A. Eaton, of California, wrote us in 1893 that in portions of 

 California where the blue gum occurs no other remedy need be sought 

 for. Further than that, he stated that no matter how plentiful the mos- 

 quitoes, a few twigs or leaves laid on the pillow at night would secure 

 perfect immunit3\ The same year Mr. W. A. Sanders, of California, 

 sent the following interesting account of the value of eucalyptus trees 

 in answer to our published request in Insect Life: 



I have the largest and oldest grove of trees of Eucalyptus globulus in this part of 

 California, and have had fifteen years of opportunity to study these trees as inseot 

 repellants, and deem it my duty to respond to your request on page 268 of Insect 

 Life. 



Thirty-three years ago I spent a portion of one summer with a Dr. McConnell, who 

 had just returned from some years of residence among the Eucalyptus forests of Aus- 

 traUa. We were in the Sequoia {Sequoia sempervirens) forest of the coast region of 

 our State. The mosquitoes were so bad that it was nearly impossible to work during 

 days when there was no wind. The doctor assured me that our common mosquito 

 was never found in the Australian Eucalyptus forests and swamps, but added. There's 

 a "spotted mosquito" nearly as bad there in some places. He, not being an entomolo- 

 gist, was unable to tell me whether the "si:)otted mosquito" was a species of the 

 genus Culex, or of some allied genus. 



The doctor being a reliable, close observer, I determined to test the antimosquito 

 qualities of the Eucalyptus; so when I began to improve my house here nineteen 

 years ago, one of the first things I did was to get a lot of eucalyptus seed from Aus- 

 tralia and plant out a grove oi the trees. The tallest of them are now over 140 feet 

 tall, and can be seen for 20 miles around. My house stajids in the midst of these 



