What stage follows the last instar in the development of a cockroach?

The correct answer is the adult stage. In the life cycle of a cockroach, after it goes through several nymphal (or instar) stages, which resemble smaller versions of the adult but lack full wings and reproductive capabilities, it eventually reaches the final instar. Following this last nymphal stage, the cockroach undergoes a molt and transitions into the adult stage.

This adult stage is significant because it represents the fully developed form of the cockroach with mature reproductive organs, allowing it to reproduce and continue the life cycle. This stage also has mature wings if the species possesses them, enabling mobility and dispersal.

The options of larval and pupal stages do not apply to cockroaches, as they do not undergo complete metamorphosis like some other insects do. Cockroaches are considered hemimetabolous insects, meaning they develop gradually without a pupal stage. The resting stage is not a defined stage in the life cycle but rather may refer to periods of inactivity, which do not represent a specific developmental phase.