The moth and the butterfly both belong to the order of Lepidoptera, the second largest class of insects. However, the moth is not classed scientifically as a separate group than the butterfly. Occasionally one sees butterflies classed as Rhopalocera, referring to the clubbing of the horns on the end of their antennae. The moth may be classed as Heterocera, meaning the horns on the end of its antennae vary according to species.
Though there are many distinctions that can be made between most moths and butterflies, there are always exceptions. For example a moth from the family Castniidae has antennae that end in clubs. The same can be said for virtually all the distinguishing factors. Some moths and some butterflies will cross over and defy general distinctions.
Yet it is still valuable to understand the distinguishing factors, realizing that not every moth or butterfly will exactly fit the profile. As mentioned above, shape of antennae are a distinguishing factor. Moth antennae show considerable variance, and often appear feathery, or look like fine fibers. Butterfly antennae tend to be straight in appearance with small rounded tips.
Both moth species and butterfly species spin cocoons. The moth cocoon may be close to the ground and is made of moth silk. The butterfly cocoon is usually harder, and may hang from trees. In fact, the distinction between most moth and butterfly species is that the moth spins a cocoon, while the butterfly spins a chrysalis, the more frequently used term for the butterfly cocoon.
Wing colors show greater variance in butterfly species. However, some moths may have bright and amazing colors as well. These moths tend to fly during the day and may exhibit color patterns of bright red and brown. One group, called the tiger moths, is actually made up of 10,000 different species that all exhibit a variety of colors. Some butterflies may defy rules and be very plain in color, like the Cabbage butterfly, which is usually white.
Generally, moth species are thought to be most active at night, which is called nocturnal. Most butterfly species are diurnal, or active during the day. Again exceptions exist. Tiger moths tend to be diurnal, atypical for moths.
One might be able to tell a tiger moth from a butterfly by examining the structure of the body. Moths tend to have furry, plump bodies. Butterflies usually have a long straight body. Moth species also tend to have wings made up of larger scales, making the wings appear thicker and furrier.
Many moth species rest with their wings opened. Butterflies may rest with their wings open for a short period of time, but longer rest periods usually involve closing the wings. This makes perfect camouflage for the butterflies because they may resemble a leaf or flower petal in the closed wings position.
There are no butterfly species that are considered pests, however, there are many moth species, which are challenging to live with. Some moth species may consume natural fibers like wool or cotton. Others may get into different grains and wreck food. They can be tenacious and unwelcome houseguests. Most of the large night moths one sees, however, are quite harmless, and should not be confused with grain or fiber eating moths, which are generally about the size of a common fly.