Named after a cyclops, a giant from Greek mythology who had one eye in the middle of his forehead, the Polyphemus moth, Antheraea Polyphemus is known for its great wingspan and the eyespots on its hindwings. Unlike Polyphemus the giant, the animal is also beautiful and benign.
Its body is also more robust and furrier than a butterfly. Polyphemus moth is a member of the Saturnidae family, which gets its name because the eyespots on some of these moths have rings around them that remind people of the rings around the planet Saturn.
Saturnidae moths are some of the largest and most spectacularly patterned moths. They’re also called royal, small emperor moth or silk moths.
Before they pupate, the caterpillars spin cocoons made of silk. In some species, this silk is used in the textile industry.
Other moths on this family tree include the luna moth, the Indian moon moth, the Io moth, the Atlas moth and the cecropia moth. Following are some more facts about the Polyphemus:
When it’s grown, it spins a cocoon about itself and turns into a pupa. As it pupates, its body undergoes extreme changes until, at the end, the adult moth breaks free of the cocoon, rests a bit after its ordeal and flies away to find a mate.
The egg resembles a tiny, oval, somewhat flat button. It’s beige or whitish with two brown bands around it. The female is careful to cement the eggs to the host plant, which can be a variety of broadleaf trees including apple trees, maple, sweetgum, hickory, birch, oak or willow.
The egg does not grow larger over time but darkens, and an observer can see the larva moving around in it just before it hatches. This about 10 days after the egg is laid. When it’s ready to hatch, the larva chews a lid in the eggshell then pulls itself out. The first thing it does is eat the empty eggshell. Then, it starts to eat the host leaf.
The larva, or caterpillar has five stages, or instars. The look of the larva changes as it moves from one instar phase to another. It does this by molting, or shedding its skin.
Unlike humans, an insect’s skeleton is on the outside of its body and can’t grow with the animal. Therefore, it is shed occasionally. The only other job of the larva is to eat and to keep from being eaten.
Two weeks later, the insect emerges as a moth. It does this by splitting the casing in the back and pushing up the top. Though the casings of other silk moths have a type of escape mechanism to allow the animal to escape, this isn’t true of the Polyphemus moth.
It has to secrete an enzyme to dissolve the silk at the front of the cocoon. Interestingly, this enzyme, which is actually called cocoonase, is secreted by the moth’s mouthparts, even though it doesn’t eat. It also uses spurs on its body to open the casing and basically struggles to get out.
Sometimes, Polyphemus moths spend the winter pupating if the weather is too cold for them to emerge or if they’re not exposed to enough light. The moths can only fly if the temperature is about 45 degrees Fahrenheit.
A person can examine a pupa to determine its sex. The female has a notch at its abdomen that the male lacks, and her antennae are separate. His antennae meet.
The first and only task of the adult moth is to find a mate, and they mate on the day they emerge from their casing. They emerge in the late afternoon, which allows their wings to dry out and stiffen before they fly off to find a mate in the early evening. The act of mating lasts for a surprisingly long time given the short lifespan of the moth. Moths can spend hours mating.
One thing that fascinates biologists about these moths is the way the females give off pheromones, which are types of hormones that attract males. These pheromones are 90 percent trans-6,cis-11-hexadecadienyl acetate and 10 percent trans-6,cis-11-hexadecadienal.
This giant silk moth is nocturnal, and the pheromones are especially potent in the two hours before dawn, and potential mates can detect them from as far as a mile away.
Eggs are laid soon after mating, with the moth usually laying one to five eggs. She can lay them in groups or attach them one at a time to the underside of a leaf. If she hasn’t found a mate within a couple of days, she stops emitting pheromones and simply releases her cargo of eggs, unfertilized as they are.
The Polyphemus species usually have two broods a year, one in early spring and the next in the late summer. However, moths in colder climates only have one brood, while those in warmer climates may produce more than two. Neither parent helps raise their offspring.
The Polyphemus Caterpillar
The first instar of the Polyphemus moth caterpillar is 5 to 6 mm long. Its body is white with black stripes, and it has a red head and bristles down the back.
As the larva grows, it turns light green and the bristles fade every time it molts. When it’s full grown, the larva is plump, with a hump at the head area. It’s 60 to 75 mm long and bright, apple green with thin yellow stripes dotted with reddish bumps and a yellow line down its abdomen.
The head is large and brown. Its colors are defense mechanisms that allows it to blend in with the leaves of its host plant. A fully grown larva eats the entire leaf, then chews the petiole, or the structure that attaches the leaf to the stem.
When it feels under threat, the Polyphemus moth caterpillar raises the front of its body in a sphinx pose. If it’s attacked, it makes a clicking sound with its jaws then vomits up the contents of its stomach. This defense mechanism seems to deter mice and ants.
As with the pupa, it’s possible to tell the sex of the larva when it’s nearly full-size. He has a black pit at the top of his ninth bodily segment. The larva does have eyes, but they are tiny and weak. It takes about five to six weeks for a Polyphemus moth instar to reach full size after it hatches.
Where do Polyphemus Moths Live?
The Size of the Polyphemus Moth
The moth has a wingspan of 4 to 6 inches. The ground color of the moth’s wings and body range from grayish to reddish brown to yellow. Sexual dimorphism, or the difference between the sexes is minimal, though the feathers on the male’s antennae are larger.
These plumose antennae allow him to detect her pheromones. The famous eyespots are ringed with white, black and yellow, and there may be areas of pink and white on the forewings and hindwings.
What do Polyphemus Moths Eat?
The moth does not eat. Its only job is to reproduce. Indeed, when it emerges from the casing, it ejects what’s left of its digestive system from its body.
The populations of Polyphemus caterpillars are kept down by a variety of natural enemies, including the mentioned mice, ants, yellow-jackets, raccoons, squirrels and birds, including the great horned owl and woodpeckers.
Woodpeckers and squirrels are particularly fond of cocoons found in trees while mice may attack those found on the ground.
When threatened, adult moths flap their wings or open them to expose the eyespots. These startle potential predators long enough for the moth to make its escape.
A long list of parasitoid insects, including parasitoid wasps, prey on the Polyphemus. These wasps include the chalcidoid, braconid, ichneumonid and proctotrupoid species.
These wasps lay their eggs on the larva itself or inside the casing. When the wasp larvae hatch, they eat and eventually kill the larva. Tachinid flies also prey on the larvae and pupae of Polyphemus.
Life Span: How Long do Polyphemus Moths Live?
Polyphemus moths live only four days. They spend the majority of their lives as caterpillars and about two weeks pupating.