Epicuticle and wax are known to constitute the outermost covering of the cuticle. This not only serves as a protective barrier against pathogenic organisms but also prevents water loss and acting as an interface between insect and its environment. Out of all these components, chitin which is a kind of heteropolysaccharide made with the polymerization of N-acetyl glucosamine through 1–4 β-linkage constitutes an important structural component of insect’s integument. Pathogen has to invade this tough integument covering to gain entry into the host.