Retinaculum (moth) on:
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Some four-winged insect orders, such as the Lepidoptera, have developed a wide variety of morphological wing coupling mechanisms in the
Other groups of moth have a frenulum on the hindwing that hooks under a retinaculum on the forewing. The retinaculum is a hook or tuft on the underside of the forewing of some
Some four-winged insect orders, such as the Lepidoptera, have developed a wide variety of morphological wing coupling mechanisms in the imago
In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...
which render these taxa as "functionally dipterous" (effectively two-winged) for efficient insect flight
Insects are the only group of invertebrates that have evolved wings and flight. Insects first flew in the Carboniferous, some 350 to 400 million years ago, making them the first animals to evolve flight. Wings may have evolved from appenda ...
. All but the most basal forms exhibit this wing coupling.
The mechanisms are of three different types - jugal, frenulo-retinacular and amplexiform. Subsec. "Wing coupling". Pp 56-60.
Jugal wing coupling
The more primitive groups of moth have an enlarged lobe-like area near the basal posterior margin, i.e. at the base of the forewing, called ''jugum'', that folds under the hindwing in flight.Frenulo-retinacular wing coupling
Other groups of moth have a frenulum on the hindwing that hooks under a retinaculum on the forewing. The retinaculum is a hook or tuft on the underside of the forewing of some moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
s. Along with the frenulum, a spine at the base of the forward or costal edge of the hindwing, it forms a coupling mechanism for the front and rear wings of the moth.
Amplexiform wing coupling
In the butterflies and in theBombycoidea
Bombycoidea is a superfamily of moths. It contains the silk moths, emperor moths, sphinx moths
The Sphingidae are a family of moths ( Lepidoptera) called sphinx moths, also colloquially known as hawk moths, with many of their caterpillars ...
there is no arrangement of frenulum and retinaculum to couple the wings. Instead, an enlarged humeral area of the hindwing is broadly overlapped by the forewing. Despite the absence of a specific mechanical connection, the wings overlap and operate in phase. The power stroke of the forewing pushes down the hindwing in unison. This type of coupling is a variation of frenate type but where the frenulum and retinaculum are completely lost.
Notes
References
{{reflist, 28emSources
* Pinhey, E (1962). ''Hawk Moths of Central and Southern Africa''. Longmans Southern Africa, Cape Town. Insect anatomy