Origin of Indirect Flight Muscles in Primitive Flies

Abstract

IT is generally supposed that among endopterygote insects the flight muscles of the adult first arise in the pupal stage. For example, in the higher Diptera (Drosophila ^1,2, Calliphora ³) the development of the indirect flight muscles is said to begin at pupation when free myoblasts adhere to or penetrate certain larval muscle fibres. In the early pharate⁴ pupa of the Neuroptera⁵ and Coleoptera^6,7, larval muscle is directly transformed into adult muscle: in certain larval muscles some nuclei degenerate and others undergo mitosis and persist as the nuclei of the adult flight muscle. In some Hymenoptera (Momonella ⁸) the adult muscles arise from free myoblasts as in the higher Diptera, whereas in others, such as the honeybee⁹, the imaginal myoblasts are contained in the larval muscle, as in the Neuroptera and Coleoptera.