The term 'Mature Insect' refers to the final stage of an insect's life cycle, known as the Imago stage. This is the adult stage of the insect, where it has reached its full size and is capable of reproducing. During this stage, the insect will typically have wings and be able to fly. The Imago stage is the longest stage of an insect's life cycle, and is the only stage in which the insect can reproduce.