HYDERABAD: The GHMC officials took up a massive programme and released oil balls in the water tank at HUDA Park under Langer Houz division in Karwan constituency on Saturday. This is the first time that the GHMC’s entomology wing organised an experiment at Langer Houz tank, as part of which they released 2,500 oil balls at a time in the pond. The oil in the balls spread quickly and in five minutes it destroyed all the breeding activities.