Tom Turpin
Professor of
Purdue University








True silkworm moths are not native to North America.  However, the largest and most-attractive moths on this continent are called giant silk moths.

The giant silk moths vary in size with wing spans from 3.5 to 6.5 inches.  These moths include the Ceropia, the Promethea and the Polyphemus, named after Greek mythology gods.

Adults of the giant silk moths do not feed.  Their mouths are barely developed and not capable of sucking up nectar as is done by most moths.  Their immature forms, however, make up for the lack of feeding on the part of their parents.  Larvae of giant silk moths are voracious eaters, feeding on leaves of trees and shrubs.  These large larvae are spectacular insects.  Most are green and ornately armed with bright-colored tubercles and spines.  Come folks think these larvae are down right ugly!

During the summer months, the larvae are small and generally go unnoticed by the public.  However, they grow quickly and as fall approaches, the small worms have turned into big worms.  Some are 5 to 6 inches in length, and are quite visible as they wander around looking for a suitable site to spin a pupal case.

These “wanderers” are sometimes discovered crawling across sidewalks or up the sides of houses.  Such encounters between humans and giant silk moth larvae elicit less than appreciative responses from most folks.  Many people are inclined to describe these large, spine-bedecked larvae as gross, disgusting or worse.

“Ugly is as ugly does.”  In this case, being ugly discourages most predators from attempting to make a meal of the creatures.  But the worm's appearance only fascinates little boys, who frequently carry them home for pets.  Whereupon, long suffering mothers will come up with a make-shift cage for the new pet.  The worm responds by spinning a cocoon.  There, snug as can be in its silken case, the worm waits for spring.  When spring comes, the ugly worm is miraculously transformed into a beautiful moth.  Could it be that the “ugly duckling” was really the larvae of a beautiful, large moth?



Writer: Tom Turpin
Editor: Olivia Maddox