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 ("imaginal" being "imago" in adjective form), the stage in which the insect attains maturity. It follows the final ecdysis of the immature instars.[1]
In a member of the Ametabola or Hemimetabola, species in which metamorphosis is "incomplete", the final ecdysis follows the last immature or nymphal stage.In members of the Holometabola, in which there is a pupal stage, the final ecdysis follows emergence from the pupa, after which the metamorphosis is complete, although there is a prolonged period of maturation in some species.[2]
The imago is the only stage during which the insect is sexually mature and, if it is a winged species, the only stage that has functional wings. The imago often is referred to as the adult stage.[1]
Members of the order Ephemeroptera (mayflies) do not have a pupal stage, but they briefly pass through an intermediate winged stage called the subimago. Insects at this stage have functional wings but are not yet sexually mature.[1]
The Latin plural of imago is imagines, and this is the term generally used by entomologists when a plural form is required –however, imagoes is also acceptable.[3]