Amphiesmenoptera is an insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

 superorder, established by Willi Hennig

Willi Hennig

Emil Hans Willi Hennig was a German biologist who is considered the founder of phylogenetic systematics, also known as cladistics. With his works on evolution and systematics he revolutionised the view of the natural order of beings...

 in his revision of insect taxonomy for two sister orders: Lepidoptera

Lepidoptera

Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...

 (butterflies and moths) and Trichoptera (caddisflies).

Trichoptera and Lepidoptera share a number of derived characters (synapomorphies

Synapomorphy

In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...

) which prove their common descent:

• Females, rather than males, are heterogametic (i.e. their sex chromosomes differ).
• Dense setae are present the wings
  Insect wing
  Insects are the only group of invertebrates known to have evolved flight. Insects possess some remarkable flight characteristics and abilities, still far superior to attempts by humans to replicate their capabilities. Even our understanding of the aerodynamics of flexible, flapping wings and how...
  
   (modified into scales in Lepidoptera).
• There is a particular venation pattern on the forewings (the double-looped anal veins).
• Larvae have mouth structures and glands to make and manipulate silk
  Silk
  Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...
  
  .

Thus the two sister orders are grouped into the Amphiesmenoptera. The group probably evolved in the Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

, diverging from the extinct Necrotaulidae. Lepidoptera differ from the Trichoptera in several features, including wing venation, form of the scales on the wings, loss of the cerci

Cercus

Cerci are paired appendages on the rear-most segments of many arthropods, including insects and arachnids but not crustaceans. Cerci often serve as sensory organs, but they may also be used as weapons or copulation aids, or they may simply be vestigial structures.Typical cerci may appear to be...

, loss of an ocellus

Ocellus

A simple eye refers to a type of eye design or optical arrangement that contains a single lens which detect light. A "simple eye" is so-called in distinction from a multi-lensed "compound eye", and is not necessarily at all simple in the usual sense of the word...

, and changes to the legs.

Amphiesmenoptera are thought to be the sister group of Antliophora, a proposed superorder comprising Diptera

Fly

True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

 (flies), Siphonaptera

Flea

Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...

 (fleas) and Mecoptera

Mecoptera

Mecoptera are an order of insects with about 550 species in nine families worldwide. Mecoptera are sometimes called scorpionflies after their largest family, Panorpidae, in which the males have enlarged genitals that look similar to the stinger of a scorpion...

 (scorpionflies). Together, Amphiesmenoptera and Antliophora compose the group Mecopterida.