|Celastrina argiolus (Lepidoptera)|
|Micropterna sequax (Trichoptera)|
Trichoptera and Lepidoptera share a number of derived characters (synapomorphies) which demonstrate their common descent:
- Females, rather than males, are heterogametic (i.e. their sex chromosomes differ).
- Dense setae are present the wings (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.
Thus the two sister orders are grouped into the Amphiesmenoptera. The group probably evolved in the Jurassic, 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, loss of an ocellus, and changes to the legs.
Amphiesmenoptera are thought to be the sister group of Antliophora, a proposed superorder comprising Diptera (flies), Siphonaptera (fleas) and Mecoptera (scorpionflies). Together, Amphiesmenoptera and Antliophora compose the group Mecopterida.
- D. Grimaldi & M. S. Engel (2005). Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5.
- M. F. Whiting, J. C. Carpenter, Q. D. Wheeler & W. C. Wheeler (March 1997). "The Strepsiptera problem: phylogeny of the holometabolous insect orders inferred from 18S and 28S ribosomal DNA sequences and morphology". Systematic Biology 46 (1): 1–68. PMID 11975347.