Illinois Natural History Survey - University of Illinois

Luna Moth

Susan Post

 

Moonlight Tango by Susan Post

On a Full Moon stage

Her heady perfume

Lures a partner

Shimmering lime, twisted tails

Circling up and around

An “Abrazo” perfected

Dawn—dancers spent

Actias luna’s twisted tango

Consummates a new
generation.

As an entomologist, if I had to choose, my favorite insect would be the Luna Moth. Growing up I remember early morning encounters in our lawn mower shed. The shed was near an outdoor light and the moths would be resting on the door or the sides of the small building.  Their lime-green wings stood out in contrast to the faded white shed. Now grown, my encounters with Luna Moths have been less often. Usually I find a wing here and there, the luna victimized by a night-feeding bat. Last June during a black lighting adventure under a full moon, a female came to the light around 10:00 pm. When we turned the light off and packed the sheet to go home, she circled up to the sky, nothing but a shadow—gone. It was magical and inspired the above poem

The Luna Moth, Actias luna, is a large, lime-green silk moth (Family Saturniidae) with a wingspan of 3 to 4.5 inches. Like its Saturniid relatives, the Cecropia and Polyphemus moths, Luna Moths have eyespots on their wings. These eyespots are used to confuse potential predators. The moths rest with the hindwing eyespots covered, but when disturbed the wings open, revealing the eyespots and hopefully startling the predator, giving the moth time to escape. Unlike it’s near relatives, Luna Moths possess elongated hindwing tails, which lend an air of aerodynamic elegance.

Luna Moths occur from east of the Great Plains to the Atlantic Coast and from Nova Scotia to Florida and Ontario to Texas. They may be found throughout Illinois. The moths prefer a forest or woodland habitat, and in Illinois their principal larval hosts are walnuts, hickories, and persimmon.

In Illinois, the moth overwinters as a pupa, emerging during May and June. Adults emerge from their cocoons in the morning and begin to inflate their wings. Since their wings are soft, the moths climb to a safe spot where they are inactive until evening. Females will release a pheromone and the males will locate her by flying upwind toward the odor source. Mating usually takes place after midnight and may last until dusk of the following day.  Females will mate only once, but males can mate each night of their short life. During their adult lifespan (7–10 days) the moths will never eat or drink as they have no mouthparts.

Once mated, the female begins to lay brownish eggs in small groups (4–7) on the underside of leaves—hickory, walnut, or persimmon. She will lay up to 300 eggs that will hatch in about a week. The larvae are lime-green caterpillars with magenta spots.  They will undergo 5 molts before pupating. Each instar (period between molts) will take about a week to complete. To pupate, the fifth instar will spin a silk cocoon, incorporating a leaf from its food source. This unattached leaf will soon die and the leaf with the cocoon will fall to the ground where it will be hidden among the leaf litter under the tree. Within the cocoon, the pupa is active, as it will wiggle about. In Illinois, there are usually 2 generations of moths with adults flying in May throughearly June and again in late July through August.

I am not the only one given to descriptive prose when encountering a Luna Moth.

In 1876, Missouri’s State Entomologist C.V. Riley wrote,
 . . . Luna, our queen of the night, entire supremacy in grace, elegance and chasteness. No other North American insect can wing this distinction from her, the delicate green, relived by the eye-spots and by the broad purple-brown or lilaceous anterior border, the soft downy hair of the body, and above all the graceful prolongation of the hind wing . . .

 

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