55 



mer wash against the scale. As yet he had not noted any serious 

 results to the vitality of the tree or to the fruit buds; but he empha- 

 sized the fact that he was not recommending this treatment to the 

 fruit growers of Maryland or any other State. 

 Dr. Howard presented the following paper: 



NOTES ON HOUSE FLIES AND MOSQUITOES. 



By L. O. Howard, Washington, D. C. 

 [Author's abstract.] 



The speaker referred in some detail to the experimental work against 

 the housefly which he has been carrying on at Washington for the past 

 two years, the results of which had just been published in Circular No. 

 30, second series, Division of Entomology, United States Department 

 of Agriculture. He also described at some length the experiments 

 against mosquitoes which had been conducted on a large scale the past 

 summer under the supervision of his office by some of the members of 

 the Eichmond County Country Club on Staten Island, N. Y. Eeferring 

 to the widespread publication during the year of a recommendation of 

 permanganate of potash as a mosquito remedy, he said: 



"One of the mosquito developments of the year has been the exten- 

 sive publication in all sorts of newspapers of an item (usually credited 

 to the Public Health Journal) which reads as follows : 



"Two and one-half hours are required for a mosquito to develop from its first 

 stage, a speck resembling cholera bacteria, to its active and venomous maturity. 

 The insect in all its phases may be instantly killed by contact with minute quanti- 

 ties of permanganate of potash. It is claimed that one part of this substance in 

 1,500 of solution distributed in mosquito marshes will render the development of 

 larvae impossible; that a handful of permanganate will oxidize a 10-acre swamp, kill 

 its embryo insects, and keep it free from organic matter for thirty days, at a cost of 

 25 cents ; that with care a whole State may be kept free of insect pests at a small 

 cost. An efficacious method is to scatter a few crystals widely apart. A single 

 pinch of permanganate has killed all the germs in a l ; 000-gallon tank. 



u The item is so obviously ridiculous upon its face that it would hardly 

 seem worth while to make any attempt to refute its statements. Nev- 

 ertheless, it has. been so widely read that definite experimentation 

 seems necessary to set the matter at rest. The unknown author's 

 ignorance of the life history of mosquitoes in the opening sentence need 

 not necessarily imply that he would not know a good remedy if he found 

 one. Careful experiments were undertaken in July with various 

 strengths of permanganate of potash in water containing mosquito 

 larvae from one to six days old. It was found that small amounts of 

 the chemical had no effect whatever upon the larvae, which were, how- 

 ever, killed by using amounts so large that, instead of using a 'hand- 

 ful to a 10-acre swamp,' at least a wagon load would have to be used 

 to accomplish any result. Moreover, after the use of this large amount 

 and after the larvae were killed, the same water twenty-four hours later 



