Rocky Mountain National Park is home to a rich moth and butterfly population. While butterflies are the glamorous branch of the family, moths are a fascinating branch. Moths can be differentiated from butterflies by their "furry" looking antennae, while the antennae of butterflies are smooth.
Why do moths fly at night? Well, actually, not all moths fly at night. Some, like the hummingbird (also called the sphinx) moth, are day-fliers throughout their range and are often mistaken for butterflies. Many moths in alpine tundra and other high altitude situations fly only in the day because they need the warmth of the sun to provide enough heat to enable them to fly.
One excellent reason for flying at night, however, is to avoid predation. Fewer predators are looking for food in moth-sized packages at night. Most flying predators of insects are sight-predators-- they rely on seeing their prey. As a result, most birds and flying insect predators such as dragonflies don't hunt at night. Bats are the major night-flying predator on moths, and can do so because they locate their prey using echo-location rather than by sight.
Moths have the advantage of being able to see exceptionally well at night. Recent research involving training moths to use colored feeders has demonstrated that they can see colors on dark nights with only the light of stars. Humans, in contrast, can detect a few color differences in bright moonlight, but generally need sunlight to perform color differentiations as well as moths can by starlight. Dark night skies protect moths from many predators.