mosquitoes could walk on the water because of surface tension. But man can’t walk on the water because the surface of the water can’t bear the weight of the man. So he gets drowned.
The health department sprays kerosene on storage water and drainages. Because on the surface of the water exists mosquito eggs. So when kerosene is sprayed on the surface of the water then the surface tension of the upper layer decreases and the mosquito eggs are drowned into water. In this way the mosquitoes will be reduced to some extent.
