A study on monthly variations of insects was made in Lower lake of Bhopal, during June 2002 to May 2004. Coleoptera, Diptera, Ephemeroptera, Hemiptera, Odonata and Trichoptera dominated insects, The density of total population of insects ranged between 201 org/sqm to 450 org/sqm having higher percentage composition of Coleoptera during most of the study period. Physico-chemical factors (water temperature, conductivity, pH and dissolved oxygen) were also estimated and their correlation with total insect density was established.