To make the Ersen-based time system more specific, you can subdivide the four main stages into smaller increments, based on observable changes in the Ersen's development or behavior. Here are a few ideas:
Sub-stages: Divide each of the four main stages (Egg, Larva, Pupa, and Adult) into smaller sub-stages that represent distinct changes in the Ersen's appearance or activity. For example, the Larva stage could be further divided into "Early Larva," "Mid Larva," and "Late Larva," each characterized by different sizes, colors, or markings.
Activity-based increments: Base time increments on the Ersen's behavior during different stages of its life cycle. For example, during the Adult stage, the Ersen might engage in specific behaviors such as feeding, mating, or laying eggs. People could use these behaviors as a reference to estimate the time more precisely.
Synchronization cues: Introduce a specific behavior or event that occurs at regular intervals within each stage, serving as a synchronization cue for the entire species. For example, the Ersen might emit a distinct sound, bioluminescent glow, or pheromone signal at regular intervals, which could be used to mark smaller time increments within each stage.
Environmental factors: If the environment in your world is influenced by the Ersen's life cycle, you could use environmental cues to create a more specific time system. For example, the Ersen's activities could cause changes in the environment, such as fluctuations in temperature, humidity, or even the color of the sky, which could be used to mark smaller time increments.
Ersen-related artifacts: People in your world could develop tools or devices that mimic the Ersen's life cycle or respond to its behaviors, providing a more precise measurement of time. For example, they could create a mechanical or biological "Ersen clock" that emulates the insect's development and provides a more accurate indication of the time within each stage.
By incorporating a combination of these approaches, you can create a more detailed and specific time system based on the Ersen's life cycle, while still maintaining the unique cultural aspects of your world.