Insect rearing bags are used for several kinds of purposes like to understand relationship between insect and plant. Under open environmental condictions insects have a choice to respond to plants in different ways. For example, insect at their immature stages might prefer to grow on leaves of different species while during adults might like to feed on to the different species than the perference during their immature stages. Using rearing bags these preferential intractions could be inferred with indirect measurements of insect's life table prameters. Bag also helps to grow fastedious insects onto the live plant materials