Imago

Just got back from wikipedia. I was trying to answer a question one friend asked: what is the stage of development after chrysalis. Of course it's butterfly, but is there a standard biological term, we wondered?

The answer is imago. Imago is synonymous with the adult (sexually mature, winged) stage of development not just in butterflies, but in all Holometabola (Endopterygota), insects that undergo Holometabolism (metamorphosis).

These include: beetles, flies, lacewings, fleas, caddisflies, mosquitos, ants, bees, and of course butterflies. There are more, but you can just go to the link for a complete list.

So it's embryo (egg), larvae (caterpillar), pupa (chrysalis), and imago (adult).

Incidentally, the plural of imago is imagines.
Also, the pupa stage of a mosquito is called a 'tumbler', FYI.