Wing is the lateral extension of

Wing is the lateral extension of Integument.
Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments, and the two pairs are often referred to as the forewings and hindwings.
Each of the wings consists of a thin membrane supported by a system of veins. The membrane is formed by two layers of integument closely apposed, while the veins are formed where the two layers remain separate.