How is a moth different from a butterfly?
The real answer is that all butterflies are specialized moths. Every species of moth and butterfly is a member of the insect group Lepidoptera – another way to say that is that they are all lepidopterans.
Scientists have created an evolutionary tree of the Lepidoptera showing how all of the species are related to each other. An evolutionary tree is also called a phylogeny.
The Lepidoptera phylogeny shows that butterflies form one unified group within all of the species of moths. This means that butterflies are really moths too.
Within the butterfly group there are several things that distinguish them from the other moth groups:
- Time of activity: A main difference is that butterflies are usually diurnal (active during the day) and the other moth groups are usually nocturnal (active at night).
- Antennae: Butterflies’ antennae are shaped like clubs, with a long shaft and a bulb at the end. The antennae of moths are more feathery-shaped or saw-edged than those of butterflies and taper at the end.
- Wing position: Butterflies hold their wings vertically above their bodies when resting. Moths hold their wings horizontally, or at their sides, while resting.
The Library of Congress has a handy guide to the differences between moths and butterflies: https://www.loc.gov/everyday-mysteries/zoology/item/how-can-you-tell-the-difference-between-a-butterfly-and-a-moth/
Did you know?
There are approximately 180,000 species of Lepidoptera known to science. Approximately 10% of those species are butterflies, and the rest are other kinds of moths!
People discover new species of butterflies every year. There are likely several times as many other kinds of moths waiting to be discovered because moths flutter through the night while lepidopterists (scientists who study lepidopterans) are sleeping.
If you’d like to help discover new moth species, why not join a mothing event! Visit nationalmothweek.org for more information about events in your area.