The term 'Adult Insect Stage' refers to the final stage of an insect's life cycle, known as the Imago stage. This is the stage in which the insect has reached its full size and is capable of reproduction. During this stage, the insect will typically have wings and be able to fly. The Imago stage is the longest and most important stage of an insect's life cycle, as it is the only stage in which the insect can reproduce and pass on its genes to the next generation.