OUTSIDE: Butterflies versus moths

Published 5:35 pm Monday, July 12, 2021

By Steve Roark

One of the joys of summer is watching bright colored butterflies flutter from flower to flower feeding on nectar.  Some moths are also beautiful to see, but most tend to be dull in color and only seen at night.  Because of this you probably notice more butterflies than moths, even though there are four times as many moth species as butterflies.

Everyone knows a moth/butterfly type insect when they see one.  They look similar and both belong to an insect order called Lepidoptera.  There are several easy ways to tell them apart.  As mentioned, butterflies are active during the day while moths are generally creatures of the night.  The antennae on butterflies are slender with a knob on the end, while on moths they look like feathers.

The wings of a butterfly tend to be bright and colorful, while moths are usually subdued.  Both forms of coloration serve to protect the insects from predators.  The moth’s dull appearance makes them less visible at night.  They keep their wings in an open position when at rest to be flat against their background and blend in better.  Butterflies keep their wings folded together, hiding their bright colors.  When disturbed, their wings open to begin flight, and in the process show a quick flash of color that can startle a predator into perhaps hesitating long enough to make a getaway.  The large dark dots you see on some butterflies (and some moths) are called eyespots because they resemble eyes that a predator might mistake for a larger animal and not attack.  These types of coloration are called “startle markings”.

Some butterflies do the reverse and have coloration on the outer edges of their wings that attract a predator towards the color.  The beauty of this system is when the bird or lizard makes a lunge for the butterfly, he targets the color of the outer wing, missing the vulnerable body and allowing the insect to fly away, leaving the predator with a mouth full of wing scales.  This type of defense is called “alluring coloration.”

One other way the two insects differ is in their feeding habits.  Both feed on the nectar of flowers using a long straw-like mouth part called a proboscis.  It looks like small coiled up clock spring when not in use but can be stretched out to probe deep into flowers.  Moths are usually strong fliers and capable of hovering in front of a flower while extracting nectar.  The typical moth pollinated flower is light colored and emits a strong-smelling nectar easily found in the dark.  The flowers are usually vertical or hanging down.  Butterflies tend to lack the ability to hover and land on the flower they are feeding on.  They are able to detect color and so the flowers they feed on are usually bright, erect, and provide platforms for landing.

Steve Roark is a volunteer interpreter for the Cumberland Gap National Historical Park.