imago (n.) Look up imago at Dictionary.com
"final or adult stage of an insect," 1797, from Latin imago "an image, a likeless" (see image (n.)). "The name is due to the fact that such an insect, having passed through its larval stages, and having, as it were, cast off its mask or disguise, has become a true representation or image of its species." [Century Dictionary]