Butterfly/Moth Difference?

Kenelm Philip fnkwp at aurora.alaska.edu
Sun May 31 03:06:19 EDT 1998

	Sharyn Fernandez notes that 'clubbed antennae' did not distinguish
butterflies from sphingid moths. There is, however, a difference between
a parallel-sided shaft ending in a club ('true butterflies' and skippers),
and a shaft that gradually increases its diameter as you go away from the
head, and then more rapidly decreases in diameter beyond the maximum
(sphingids). The character 'clubbed antennae' is shorthand for the
parallel-sided shaft ending in a club.

	The old classification had Rhopalocera (clubbed antennae) for
butterflies and Heterocera (other antennae) for moths--which includes
all the other shapes: feathered, tapered, gradually thickening and thinning.
This is a very artificial classification, and is not in current use. It
is safer to simply say that butterflies are certain families within the
Lepidoptera, contained in the two superfamilies Hesperioidea (skippers)
and Papilionoidea ('true butterflies). These two superfamilies have
clubbed antennae (as defined above), and lack the frenulum/retinculum
that link the fore and hind wings in most moths (except some of the older
groups, as the Hepialidae). There is one skipper that has a frenulum,
so one cannot depend on those two characters alone in all cases. But
they will work for most commonly encountered lepidoptera in North America.

	Butterflies belong to the suborder Ditrysia. Within that suborder,
they belong to the Macrolepidoptera (superfamilies Geometroidea, Noctuoidea,
Bombycoidea, Sphingoidea, Hesperioidea, and Papilionoidea). There are a
number of characters that differentiate butterflies from the other macro-
lepidoptera (see Scott, 'Butterflies of North America', page 97). Diurnal
flight, although a major feature of butterflies, cannot be used to distin-
guish them from moths, since a number of moths also fly in the daytime.

	Rather than looking for one or two universal characters that sep-
arate all butterflies from all moths (basically a hopeless task), it's
better to learn the butterfly families. Once you can recognize an insect
as belonging to the family Lycaenidae, you already know it's a butterfly!
Moths are a _very_ diverse group, which is what makes it so difficult to
separate butterflies from all moths by just a couple of characters. Some
moths have chewing mouthparts, for example. 'Earlier' groups of moths
also lack the frenulum. But such moths are not likely to be confused with

	Fernandez also mentions fuzzy vs. smooth caterpillars. That is
no use at all! Many moth larvae are smooth. Many butterfly larvae are
hairy (lycaenids) or fantastically spiny (nymphalids).

							Ken Philip
fnkwp at aurora.alaska.edu

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