Are bird wings and butterfly homologous structures?

Bird wings and butterfly wings are not homologous structures, rather they are analogous structures. Homologous structures are those structures that have a similar embryonic origin, composition and form but may have different functions. For example, the forelimbs of humans, bats, horses and whales are homologous structures as they all develop from the same embryonic limb buds and have similar bone structure even though they have different functions. On the other hand, analogous structures are those structures that have similar functions but have different embryonic origins and compositions. Bird wings and butterfly wings are analogous structures as they both serve the function of flight, but they have different embryonic origins and compositions. Bird wings are derived from the forelimbs of reptiles, while butterfly wings are outgrowths of the body wall and are supported by veins.