The Chennai Corporation for the second time in a year will experiment with biocide to control the mosquito menace prevalent in many parts of the city. The earlier initiative to use the bio-larvicide was in April 1997 where it was sprayed in all the 11 waterways and in inland areas where there was water stagnation. The larvicide was expected to rid the residential areas of the menace within one to two km radius from the spraying spot and minimise the problem in other areas.