Io Moth Facts: Their Caterpillar Sting Is More Painful Than That of a Bee

With its vivid colors and intricate patterns, the Io moth captures the imagination of all who lay eyes upon it. But don’t be fooled by its ethereal beauty; this creature boasts a hidden strength and a potent defense mechanism that makes it a true marvel of nature. Step into the realm of this extraordinary insect and unveil the facts behind its enchanting allure.

Io moth
Scientific name: Automeris io
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Saturniidae
Genus: Automeris

1. They’re often mistaken for peacock butterflies

The Io moth, commonly found in different regions, is a silkmoth of medium to large size. It boasts an impressive wingspan, ranging from 2.5 to 3.5 inches (63–88 mm). The females tend to be larger than the males while the feathery antennae of the males is significantly larger than that of females.

In terms of appearance, the male and female Io moths exhibit distinct differences in their forewing colors. The male Io moths showcase vibrant yellow forewings, whereas the females display darker shades of yellow, rusty red, purplish, or brown on their forewings. Furthermore, the females’ forewings are often broader and more pointed in shape.

The male has bright yellow color

One of the most highlighted features of these moths is the prominent eyespots on their hindwings. This characteristic makes Io moths look like peacock butterflies. That’s why they are also called peacock moths.

These eyespots display a dark black or brown coloration, encircled by a bluish or grey iris, with a distinctive white center. The females typically possess larger and rounder eyespots compared to the males.

Fun fact:
The name ‘Io’ finds its roots in Greek mythology, specifically in the tale of Zeus, the king of gods. In Greek mythology, Io was a mortal woman who became one of Zeus’ lovers and happened to be his wife’s priestess as well. To protect Io from his wife’s wrath, Zeus transformed her into a cow.

2. Habitat

The io moth can be found across North America, ranging from Mexico to numerous regions in the United States (such as Colorado, Texas, and Utah) and extending to Canada, including provinces like Ontario and Quebec.

The female moth

This species is highly adaptable, making it one of the most prevalent and widely dispersed moth species in North America. It can thrive in diverse climates and habitats, such as suburban areas, gardens, deciduous forests, orchards, backyards, and shrubbery within grasslands and meadows. Their remarkable capacity to flourish in a multitude of environments is a key factor in their extensive range across different regions.

Fact: Spiritual meaning and symbolism
The io moth is a symbol of change, transformation, rebirth, and new beginnings. It represents the journey of life and the ability to adapt. It signifies hope and perseverance, reminding us that even in difficult times, there is potential for growth and fresh starts.

3. They are voracious

Upon hatching, the caterpillars eat their own eggshells and proceed to feed on plants. The Io moth caterpillars exhibit a highly polyphagous nature, meaning they have a diverse diet that encompasses a wide range of plants, including grasses, deciduous trees, shrubs, herbaceous plants, and conifers.

The io moth larvae are eating

Their diet contains at least sixty different varieties such as cherry trees, elm, sassafras, pear trees, maple, hackberries, aspen, hibiscus, alder, hickory, ribes, redbuds, blackberry plants, wisteria species, and willow. Their voracious appetite can defoliate trees entirely.

In contrast to caterpillars, adult Io moths do not have functional mouthparts to eat.

4. They are dangerous

Both Io moth caterpillars and adults have their own ways to protect themselves from predators like spiders, birds, insects, and mammals.

The larvae have venomous spines distributed throughout its body. When these spines come into contact with predators or human skin, they can detach and release venom. When these spines penetrate the skin, they can cause a sensation similar to a severe bee sting, resulting in hours of persistent pain. Additionally, the breakdown of chitin in the skin may trigger an inflammatory response. However, some predators have developed immunity to these effects.

If you are stung by io moth larvae, it is recommended to wrap the affected area with cellophane tape. This method may help in removing the spine tips. However, if you are uncertain about the severity of the sting or the affected areas become worse, you should seek medical advice for caterpillar sting treatment.

The Io moth adult, on the other hand, uses the eyespots on their wings as a defense mechanism. In the daytime, they remain motionless, blending in with their environment. When alarmed, they instinctively retract their heads and reveal their eyespots on the back wings. This can repel or surprise potential threats such as birds or spiders, granting them a chance to get away.

Thanks to the coloration and eyespot pattern, they can live longer than other moth species that lack these characteristics.

5. Life cycle

The Io moth has a nocturnal lifestyle as an adult, taking flight from early May until September, solely during the night. During the day, they find refuge on tree trunks or branches, engaging in restful activities. They do not eat and spend the rest of their time looking for partners. Their search for mates begins shortly after sunset and extends until the early hours of the night. These moths exhibit a fascination with lights.

To attract males, the female Io moths release pheromones into the air, creating an alluring scent. Once emitted, they patiently wait for potential partners to approach them, engaging in copulation with those willing to mate. After breeding for 3 – 5 days, she becomes slightly more active and proceeds to deposit a clutch of 50 to 250 pale white, oval eggs on suitable host plants.

The female lays eggs on the underside of the host plants

After laying eggs, the female dies. After females lay their eggs, their life cycle reaches its conclusion. The eggs undergo fertilization and gradually transform, acquiring a black spot and shifting towards an orange/brown hue as they mature. Within 2 to 3 days, these eggs hatch into larvae.

During their early stage, the larvae display an orange coloration and are adorned with spikes. They tend to stay in groups, occasionally forming lines. However, as they progress in their growth, they tend to become more solitary and have different colors. They exhibit hues ranging from yellowish green to bluish green, adorned with a vibrant red-and-white stripe running along their sides. Their bodies are adorned with clusters of green spines, reminiscent of the prickly pear cactus.

The young larvae io moth are yellow-orange

During a span of four weeks, caterpillars experience five stages of growth as they continuously feed. Once they reach full maturity, they proceed to create papery brown cocoons, which can be found in crevices, on plant leaves, or on the forest floor. The moth will emerge from the cocoon within a few months or after overwintering, depending on the seasons and places.

Io moths in the northern usually have one generation per year, whereas moths in the southern produce multiple generations within a single season.

The lifespan of Io moths is quite short. They can live for only 7 – 14 days, during which they must seek a suitable partner and create the next generation.



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