Editing Metamorphosis (section)

=== Evolution ===
The earliest insect forms showed direct development ([[ametabolism]]), and the evolution of metamorphosis in insects is thought to have fuelled their dramatic radiation (1,2). Some early ametabolous "true insects" are still present today, such as [[Archaeognatha|bristletails]] and [[silverfish]]. [[Hemimetabolism|Hemimetabolous]] insects include [[cockroach]]es, [[grasshopper]]s, [[dragonfly|dragonflies]], and [[Hemiptera|true bugs]]. Phylogenetically, all insects in the [[Pterygota]] undergo a marked change in form, texture and physical appearance from immature stage to adult. These insects either have [[Hemimetabolism|hemimetabolous]] development, and undergo an incomplete or partial metamorphosis, or [[Holometabolism|holometabolous]] development, which undergo a complete metamorphosis, including a [[pupa]]l or resting stage between the [[larval]] and adult forms.<ref name="autogenerated143">Gullan, P.J. & Cranston, P.S. 6.2 ''Life History Patterns and Phases in The Insects: An Outline of Entomology''.  pp. 143–153. 2005 by Blackwell Publishing</ref>

A number of hypotheses have been proposed to explain the evolution of holometaboly from hemimetaboly, mostly centering on whether or not the intermediate stages of hemimetabolous forms are homologous in origin to the pupal stage of holometabolous forms.