Introduction

Butterflies and moths may look very similar on the surface, but they are actually quite different. Both are insects that start as caterpillars, then construct a cocoon, and within that cocoon transform themselves from worm-like creatures to flying insects.  It is easy to confuse these two amazing types of animals. Both moths and butterflies come in amazing varieties of patterns, colors, and sizes . This paper will review the best ways to distinguish between moths and butterflies for easier recognition.

Discussion

There are several ways to distinguish between  a moth and a butterfly.  The easiest differences to observe are (1) differences in the antennae of the insect; (2) differences in when the animal is active.  More subtle differences include (3) colors; (4) wing structure; and (5) position of wings when at rest.  Each of these will be discussed below.

In terms of the most obvious differences that apply across most moth and butterfly species, the first of these is the shape of the antenna.  In a moth, the antenna usually looks “feathery” whereas in butterflies, the antenna generally has some kind of thick knob or even a hook at the tip (Australian Museum, 9 July 2009).  The thickened knob or club at the end of a butterfly’s antenna may be either readily visible or harder to see, but all butterflies have that club-shaped end to the antenna (Big Sky Institute at Montana State University, n.d.). A very few moth species may have the club antenna, but no butterfly has a feathery antenna (Australian Museum, 9 July 2009).

The second easily identified difference between butterflies and moths is the time of day when they are active.  Usually butterflies are active during the day (i.e., they are diurnal), while most moths are active at night (nocturnal) (Wikipedia, 7 May 2011; Butterflies and Moths, 2000).  There are exceptions to this rule, however.  For example, the gypsy moth and the “sunset” moths are both active while the sun is up (Wikipedia, 7 May 2011; Butterflies and Moths, 2000).

If these characteristics do not differentiate butterflies and moths, the more subtle differences may confirm.  The first of these is color.  Moths usually have flat, matte colors, most often gray, brown, black, or white.  They also tend to have patterns that tend to camouflage them during the day by allowing them to mimic the bark of their typical resting places.  while butterflies are more often brightly colored, which helps them find mates from visual patterns (Wikipedia, 7 May 2011).

Wing structure may also help differentiate between moths and butterflies, though this is more difficult to notice.  Typically, moths front and back wings are connected so the wings work in unison.  In butterflies, the front and rear wings tend to be independent (Library of Congress, 23 August, 2010)

Yet another difference between the two is the position they take at rest.  Butterflies usually rest with their wings vertical above their body, while moths tend to rest with their wings spread horizontally.  This is not guaranteed, however, since a few butterflies sometimes rest with their wings spread horizontally and some moths sometimes rest with their wings vertically, particularly if space is limited (Wikipedia, 7 May 2011).

Conclusion

While moths and butterflies look very similar to each other, differences do exist.  The antennae, time of activity (i.e., nocturnal vs. diurnal activity), colors, wing structure, and resting position all tend to differ between the two types of insects. While none of these differences make a 100% positive identification individually, since exceptions to each of them exist,  if multiple characteristics point to moth or butterfly, it can be assumed that the identification is almost certainly correct.

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