66 Proceedings Ninth Annual Meeting 



only thirty-one deaths from malaria with about 2,000,000 men in 

 southern camps. 



The work of mosquito control of stock ponds is being extended, 

 and fish hatcheries (Gambusia aifinis) are being established in or 

 near many county seats. Large signs are being erected near these 

 hatcheries to encourage the population to^ use the fish. 



Yellow fever is yet present in the oil fields on the coastal plain 

 of Mexico between Tampico and Vera Cruz, within thirty-six 

 hours travel of the Texas border. The travel from Mexico to 

 Texas is mostly through the border towns of Laredo and Browns- 

 ville. In those cities the wells, cisterns and water barrels are kept 

 free from mosquito larvae of the yellow fever mosquito by means 

 of this same top minnow with satisfactory results. 



Those of you who are interested in Anopheles control measures 

 would probably find points of interest in the Proceedings of 

 Malaria Field Workers, Bulletins 104 and 115, United States 

 Public Health Service. Each year many malaria field workers 

 meet with the Southern Medical Association and exchange ideas. 

 The next meeting will be held at Chattanooga, Tennessee, in 

 November, 1922. At the last conference an interesting paper on 

 ''Arsenic as a Larvicide for Anopheles Larvae" was presented 

 by Dr. M. A. Barber. It contained this formula : *'One part of 

 commercial Paris green thoroughly mixed with 100 parts by 

 volume of road dust." This treated road dust is thrown into the 

 air and carried by light air currents from twenty to forty feet. 



As you go along a dusty country road if you get on the lee- 

 ward side of a Ford as it goes by, you will find yourself sprinkled 

 with dust. Well, it is merely the application of that principle. If 

 in that dust we had i per cent, of Paris gfeen yoju' would also be 

 sprinkled with the Paris green. The Anopheles larvae take in the 

 dust with the Paris green, apparently spit out the dust and retain 

 the Paris green. This is just what we want them to do. 



It should be applied on a sunny day after the dew is off the 

 grass. With Paris green at 25 cents per pound, it costs about 

 seven-tenths of a cent to treat 1,000 square feet of water surface, 

 and is especially useful in wet places containing vegetation or 

 other obstacles when such water bodies cannot be easily drained. 

 By the barrel, Paris green costs 22 cents per pound. Six-tenths 

 of a cubic inch of it with 100 times its value of road dust will treat 

 about 1,000 square feet of grass-covered water surface. This 

 treatment is non-poisonous to mosquito larvae other than Anop- 

 heles, and does not harm fish or other aquatic life — it most cer- 

 tainly destroys Anopheles larvae. 



