subimago

Etymology

sub- + imago, after German Subimago.

noun

1. (zoology) 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.
   Subimago, Fem.—Dull piceous: antennæ black: abdomen more than twice the length of the thorax: setæ brownish testaceous, mutilated: legs dull testaceous; fore-legs brown: wings gray; veins black, not strongly marked. 1853, Francis Walker, Catalogue of the Specimens of Neuropterous Insects in the Collection of the British Museum, page 538
   The subimago (a winged, but usually sexually immature stage) in the life cycle of mayflies is unique among living insect orders. The Ephemeroptera have two winged-instars, the subimago and the adult (or imago). 1996, Richard W. Merritt, An Introduction to the Aquatic Insects of North America, page 126
   Subimagos emerge at the surface, fly to a support, molt immediately to the adult stage, live only a few hours, swarm, and mate shortly after ecdysis. 2009, James H. Thorp, Ecology and Classification of North American Freshwater Invertebrates
   Subimagines flutter away immediately and rest at protected sites near the stream for up to 2-3 days, until the molt to the very short-lived adult occurs. 2011, Rüdiger Wagner, Central European Stream Ecosystems: The Long Term Study of the Breitenbach