Wing coupling

Some four-winged insect orders, such as the Lepidoptera, have developed a wide variety of morphological wing coupling mechanisms in the imago which render these taxa as "functionally dipterous" (effectively two-winged) for efficient insect flight. All but the most basal forms exhibit this wing coupling.^: 4266

The mechanisms are of three different types - jugal, frenulo-retinacular and amplexiform.