Luna Moth

                                                                Luna Moth Adult  [Internet Photo]

The Luna Moth is a spectacular moth, for me our most beautiful moth.  It is very large with a wingspan of 8 to 11.5 cm (3 to 4.5 inches).  Rarely it can get as large as 17 cm (7 inches).  I saw one this past weekend (June 6) in a hardwood forest at Scotch Settlement, York County.  Believe me, it is a mouth-dropping experience.  It flew past me from behind and quickly made its way among the deciduous leaves just above eye level.  Its awesome light lime colour was remarkable and the trailing tails on its hind wings were waving back and forth as it flew past.  It looked to be about 15 cm (6 inches) across.  Unfortunately it did not give a photographic opportunity.  As shown in the photo above, the Luna Moth  has simulated eye spots on both the fore- and hind wings.  The body is white.  The antennae are feathered, moreso in the males.

I have not seen many Luna Moths in my lifetime.  After reading about their life history I now know why.  The adults are very short lived.  In fact, they are only around for about a week.  So let's look at the life history.  The eggs are laid under leaves of deciduous trees.  In New Brunswick the favoured trees are maple, oak, willow and white birch.  (See how important it is to plant native trees).  In our part of North America Luna Moths go through only one life cycle per year.  Further south they can manage 2 or 3 cycles.  The eggs hatch into larvae which then go through five stages.  They feed, grow and then pupate repeatedly until they get large enough to metamorphisize into adults.  

                                                        Luna Moth Larva (Caterpillar)  [Internet Photo]

The larvae grow up to 70-90 cm in length (2.8-3.5 inches).  The larvae go through 5 cycles before becoming a cocoon.  Most stages look similar.  The black spots are sometimes burgundy in colour.  All cycles are carried out in the same deciduous tree.  After the fifth cycle (instar) the larva crawls to the ground and forms a cocoon in the leaf litter under the tree.  The adults then emerge in about 2 weeks from the cocoon.  It takes 2 to 3 hours for the adults to inflate their wings and harden their structure so they can fly.  The adult females fly to a preferred tree and then emit their pheromones to attract a male.  She usually accepts the first male that arrives.  The breeding process takes place around midnight and it takes about 2 hours.  The female usually dies after laying her eggs.  The male remains alive for a few more days in order to breed more females.  The adults are nocturnal and remain alive for only 7 to 10 days.  No wonder we rarely see them.  

Luna Moths have a few interesting defence mechanisms.  The larvae make a clicking noise when in danger.  These sounds extend into the ultrasound frequencies but are also audible to humans.  They also regurgitate intestinal contents as a deterrent.  Bats prey on Luna Moths and research has shown that their trailing long tails on their hind wings scramble echolocation helping to protect them from bats.  

Luna Moth populations are threatened by pesticides.  Another insult has come from well-meaning attempts to control the gypsy moth.  A fly was introduced from Europe to help control the gypsy moth and unfortunately adversely affected the Luna Moth as well.  

Luna Moths, Actias luna,  are members of the Saturniidae family, giant silk moths.  They have been mentioned in Greek mythology, modern pop music and literature. A Luna Moth was featured on a US postage stamp in June, 1987.