What is "subimago"

Subimago \Sub`i*ma"go\, n. [NL. See Sub-, and Imago.] (Zo["o]l.) A stage in the development of certain insects, such as the May flies, intermediate between the pupa and imago. In this stage, the insect is able to fly, but subsequently sheds a skin before becoming mature. Called also pseudimago.

n. (context zoology English) A stage in the development of certain insects, intermediate between pupa and imago, during which the insect can fly but must shed a skin before becoming mature.