The Polyphemus moth ( Antheraea polyphemus) is a North American member of the family Saturniidae, also known as the giant silk moths. This species is widespread across continental North America, with populations found throughout subarctic Canada and the United States. The moth is easily identifiable by its tan color, average wingspan of 15 cm (6 in), and large, purplish eyespots on its two hind wings, reminiscent of the Cyclops Polyphemus from Greek mythology.
Life Cycle and Instars
The life cycle of the Polyphemus moth begins with small, light brown eggs laid on the leaves of host trees. These eggs have a distinctive appearance, often described as slightly flattened and resembling brown Oreo cookies. After hatching, the caterpillars undergo five instars, which are the stages between each molting as the caterpillar grows. Initially, the tiny caterpillars are yellow, maintaining this coloration until the 5th instar when they transform into a bright green hue, almost fluorescent, adorned with small red and silver spots on their sides. Each of these spots features two to five hair-like structures called setae.
The Importance of Host Plants
Polyphemus moths are polyphagous, meaning their caterpillars can feed on a wide variety of plants. The choice of host plant can sometimes influence the survival and development of the caterpillars. While different references may offer varying lists of suitable plants, it's important to recognize that not all listed plants are equally compatible or preferred by the caterpillars. Some plants may be primary preferences, while others serve as secondary options when the preferred food source is unavailable.
Diet Breadth
Polyphemus caterpillars are known to feed on a variety of leaves. A member of the public recently brought some tiny caterpillars to Carnegie Museum of Natural History’s Section of Invertebrate Zoology for identification. This culture was reared on oak leaves, but they also thrive on many other kinds of host plants. These include:
- Apple
- Ash
- Birch
- Dogwood
- Elm
- Hazel
- Hickory
- Maple
- Rose
- Willow
Antheraea polyphemus is also known to feed on a variety of plants including American elm, beech, birch, grape, hickory, honey locust, lemon, maple, oak, pear, plum, walnut, etc.
Read also: Feeding Giant Leopard Moth Caterpillars
Host Preference
Host preference can vary depending on the geographic location where the parent moth originated. For example, a mated female collected in a maple forest may lay eggs that produce caterpillars with a primary preference for maple and similar species. If a mated female is collected in a pine forest with some sweetgums and oaks were available here and there and the exact location where the mated female had sweetgums all over the place, then caterpillars only fed on sweetgum.
Experimentation with Host Plants
Rearing caterpillars can sometimes be challenging, as demonstrated by attempts to raise other moth species such as Actias luna, Dryocampa rubicunda, Eacles imperialis, and Automeris io on red oak. Despite being known to feed on red oaks, these caterpillars refused to eat the oak leaves and eventually died of hunger. This highlights the importance of providing caterpillars with their preferred host plants to ensure their survival and healthy development.
Cocoon Construction and Pupation
Many Polyphemus moth caterpillars pupate in the leaf litter. Before pupation, Polyphemus moth caterpillars spin a cocoon out of silk (hence their name ‘giant silk moth’) on a leaf in a tree. It is visible in the image how the caterpillar spun its cocoon in the oak leaf. The cocoon then drops to the ground in autumn when the leaves fall. Inside of each cocoon is a dark brown pupa which the adult moth will come out of. Some species like the Polyphemus moth spin a cocoon, but there are species that don’t. The caterpillars typically reach their 5th instar before seeking a suitable location to pupate.
Adult Stage
Adult Polyphemus moths should eclose around May or June and spend the winter in the pupal stage. After emerging, the adult moths have a short lifespan of 7 to 15 days dedicated to finding mates. Notably, adult Polyphemus moths have vestigial (atrophied) mouthparts and do not feed at all during this stage.
Identifying Male vs. Female
An easy way to distinguish male from female giant silkworm moths is by observing their antennae. Male Polyphemus moths have wider, feathery antennae compared to females. This adaptation allows males to detect female pheromones over long distances, aiding them in their search for a mate.
Read also: The Majestic Monarch Article
Generations per Year
The number of generations of Polyphemus moths per year varies depending on the geographic location. In the southern regions, there are typically two generations of moths, while in the northern regions, there is only one. Some sources suggest that in Missouri, there may be as many as three generations per year.
Distribution and Habitat
The Polyphemus moth is widely distributed in North America. They are found in south Canada, Mexico, and the United States except Arizona, Nevada, Alaska, or Hawaii. These moths typically inhabit forests and woodlands, where they can find their preferred host plants.
Conservation
Polyphemus moths are not dangerous and do not sting. It is best to admire them from a distance and avoid handling them. These moths have a limited time to find a mate, so it's important not to waste their energy.
Read also: What do Forest Tent Caterpillars Eat?
tags: #polyphemus #caterpillar #diet #and #host #plants