CBSE Class 10 Answered

Insect wings are outgrowths of the insect exoskeleton that enable insects to fly. Insect. Their wings develop as evaginations of the exoskeleton during morphogenesis but they become fully functional only during the adult stage of an insect's life cycle.  The wings may be membranous, parchment-like, heavily sclerotized, fringed with long hairs, or covered with scales.  Most insects have two pairs of wings, some like flies and mosquitoes have one pair of wings. Most insects have membranous wings; such wings are very thin and like cellophane. In most cases, a characteristic network of veins runs throughout the wing tissue. The wings are not supported by bones.

Wings of birds on the other hand are modified forelimbs. A bird's wing is covered with contour feathers that are specialized for flight. The avian wing contains the usual arm bones of reptiles and mammals, but in a highly modified form. Many of the bones have become fused, and the skeleton of the hand has undergone considerable simplification. The humerus is rather short compared to the total length of the wing. The radius and ulna form the support for the mid-wing. The outer wing or hand bones are highly fused for strength and feather support. There are only three fingers. These fingers have reduced phalanges.