1. 1. Paris green was used as a larvicide on an inland hilly estate where A. maculatus was the carrier-and where most of the water treated was moving, more or less rapidly. 2. 2. Three different diluents were tried, viz., lime, talcum and soapstone powder. 3. 3. The strength of the mixture was one part of Paris green to ninety-nine parts of diluent by volume. 4. 4. Distribution was carried out by mechanical blowers and sprayers. 5. 5. The application was checked twenty-four hours afterwards. For one month it was checked forty-eight hours afterwards. 6. 6. There was an increase in breeding places-most of which were found in moving water. 7. 7. There was an increase in larvæ, many of them being over two days old. 8. 8. In spite of treatment of epidemics with plasmochin and quinine, the malaria rate was higher than during the previous year. The rise was more or less consistent, pointing to constant infections. 9. 9. The morbidity rate, death rate and infantile mortality were apparently not adversely affected, but in view of the treatments given with plasmochin, they are of no help in deciding the value of Paris green. 10. 10. There was a distinct fall in anti-larval costs, but the total anti-malarial costs were still high on account of the treatments necessary for epidemics of malaria. 11. 11. The advantages and disadvantages of Paris green are discussed.