How do you tell a butterfly from a moth? Both moths and butterflies are in the order Lepidoptera, but there are general differences that can help you know which is which.
Here are a few overall rules that can be used to distinguish moths from butterflies. Of course, there are always exceptions to the rules.
Antennae
Moths have simple thread-like or ‘feathery’ antenna without a club.
The antennae of the Polyphemus moth (Antheraea polyphemus) have hairlike olfactory receptors that are used to detect female sex pheromones.
Butterflies have a thickened club or hook on the tip of the antenna.
Antennae of the Great Southern White butterfly (Ascia monuste) have blue knobs at the end. Butterfly antennae are used for the sense of smell and balance.
Exceptions: Several families of moths have antennae with clubs, most notably the Sun moths (Castniidae).
When I saw this Wood Nymph moth (Cercyonis pegala), I had no idea what it was. It looks like bird poop, perhaps to discourage birds and other predators from eating it.
Butterflies usually have brighter colors.
The Blue Morpho (Morpho menelaus) is among the largest butterflies in the world with wings spanning from five to eight inches. Their vivid, iridescent blue coloring is a result of the microscopic scales on the backs of their wings, which reflect light.
Exceptions: Many moths are brilliantly colored, especially day-flying moths.
When we think of moths sometimes we think they are not as colorful as butterflies. The Madagascan Sunset moth (Chrysiridia rhipheus) is a day-flying moth and is considered one of the most colorful. Madagascan Sunset moths are found only in tropical forests on the island of Madagascar off the southeast coast of Africa.
Resting posture
Moths hold wings flat when resting.
The Luna moth (Actias luna) is probably the best-known of the American silk moths.
Butterflies hold wings together above their body when resting.
A Malachite butterfly (Siproeta stelenes) resting with its wings closed. The colors of the wings are a bit duller on its underside and help it to camouflage itself.
Exceptions: Many moths, including Geometrid moths (Geometridae spp.) hold their wings up in a butterfly-like fashion when resting. Butterflies in the Lycaenid subfamily Riodininae, and Skippers in the subfamily Pyrginae hold their wings flat when resting.
Pupae
Moths spin a cocoon before they pupate.
This moth used the hair from its body to create a cocoon.
Butterflies will shed their skin for the last time and reveal a chrysalis.
The Monarch caterpillar hangs in the “J” position before it sheds its skin.
Exceptions: Many moths do not spin a cocoon; many butterflies and skippers form a silken shelter, often with plant leaves.
Butterflies are diurnal and are active during the warmth of the day.
These Tiger Longwings (Heliconius hecale) are basking in the sun. The optimum body temperature for a butterfly to fly is between 82° and 102° F (28° and 39° C). They regulate their body temperature and keep it warm by practicing behavioral tactics such a shivering their wings or basking in the sun.
Exceptions: A few butterflies are active at dusk; many moth species fly during the day.
Not all moths are nocturnal. Polka Dot Wasp moths (Syntomeida epilais) fly during daylight hours. Click on the link to read more about this moth: http://www.floridanaturepictures.com/butterflies/polkadot_wasp_moth.htmThe Evening Brown butterfly (Melanitis leda) is a common species that flies erratically at dusk. Here it’s sipping on sap from a tree.
