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 final ecdysis of the immature instars.^[1]

In a member of the Ametabola or Hemimetabola, 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, 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 extra 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 – however, imagoes is also acceptable.^[3]

• Imaginal disc