Chironomids are cosmopolitan, diverse aquatic insects of freshwater systems. Bioindicators provides information about ecosystems that are very sensitive to pollutants in the environment. Their morphology, physiology and behavior are affected by the concentration of certain pollutants or it may die. Polytene chromosomes of these midges may be used as biomarkers for heavy metal pollution. Aberrations in polytene chromosomes correlate with degree of pollution stress and express diverse response to toxic agents.