Which transformation stage is characterized by a significant change from a larva to an adult mosquito?

The pupa stage is a critical transformation phase in the life cycle of a mosquito, marking a significant transition from larva to adult. During this stage, the pupa undergoes drastic morphological changes, but it does not feed. Instead, it prepares for adulthood. The organism is often referred to as a "tumbler" because it can move by expelling water and is generally more mobile than the larva stage.

This stage is also critical because it is when the developing mosquito is formed within a protective casing and is undergoing all the necessary changes to emerge as a fully developed adult. The metamorphosis happening within the pupa includes the development of wings, the formation of adult mouthparts, and structural changes to prepare for flight and reproduction.

The other stages mentioned focus on different aspects of the mosquito's life cycle: the egg stage begins the life cycle, the larva stage is primarily about growth and feeding, and the nymph stage is not a part of mosquito development as it pertains to other insects in their life cycle. Hence, the pupa stage is uniquely characterized by this significant transformation leading to the emergence of an adult mosquito.