Here we see our little Alice “in the blue.” Snake scales are made of keratin, the same stuff your fingernails are made of, a sort of “organic plastic.” One of the limitations having non-living skin is that it can’t grow, so it eventually becomes snug & uncomfortable. Every few months the snake has to grow an entirely new skin.
During that process, fluids build up beneath the old skin while the new skin develops beneath. This gives the snake a darker appearance overall, but it’s especially visible in the transparent scale over their eye (aptly called the “spectacle”). It gives the eye a pale bluish hue, which we call being “in the blue” or just “in blue.” Eventually the fluid clears and the snake almost looks normal again. The actual shedding usually occurs the following day or so after clearing up.
Snakes don’t have great eyesight to begin with, but when they are in blue, they’re practically blind. Snakes in blue will tend to be more nervous & defensive and are more likely to bite, so it’s always best to leave them be. Alice quickly returned to the safety of her cave after this quick check-up.
