A darkening sky sends bees and butterflies to their rest out of harm's way. Evening twilight is the stimulus for slugs to emerge from daytime inactivity to course over lawn and garden, laying trails of slime that lessen friction between their soft bodies and abrasive soil. During the night their file-like tongues rasp tender leaves, leaving damaged foliage to dismay gardeners the next morning who want the most out of a closing season. The interval between day and night tells some of the larger beetles to crawl up stems and trunks, split wide their hard protective wing covers that lend shape to their bodies, snap open delicate wings hidden underneath, and fly off into the dark with a buzz. As light fades, moths cluster around porch lights in increasing abundance and astonishing variety.
Frogs begin their insistent clamor, and salamanders come out of hiding to hunt upon dew-wet ground.
It is time for a changing of the guard. Twilight is when raccoons, skunks, foxes, porcupines, and woodchucks emerge to forage most busily, to hunt and seek one another. Most of them do well in both dim light and darkness, because keen senses other than vision are more than sufficient to determine where they are going and what they need to do. We should envy them, because we aren't very good finding our way through the woods at night, although I remember reading that when slaves escaped in the South and headed north to liberty, they dared not reveal their presence with lanterns and felt their way through the forest with arms outstretched, lightly touching trunks to determine the direction where freedom lay by the heavier growth of small encrusting plants on the northern side of trees. Although night in nature can be threatening to us, it's not to many other creatures.