Arctic woolly bear moth facts for kids

The Gynaephora groenlandica, also known as the Arctic woolly bear moth, is a special type of moth found in the very cold Arctic regions. These areas include parts of Canada, Greenland, and Wrangel Island in Russia. This moth is famous for its super slow life. Its caterpillar stage can last up to 7 years! Each spring, the caterpillar sheds its skin.

For most of its life, this moth stays as a caterpillar. It goes into a deep sleep called diapause every year. This sleep helps it survive the extremely long and cold winters, where temperatures can drop to -70 °C. The Arctic woolly bear moth also likes to sunbathe. This helps it control its body temperature and digest food. Female moths usually don't fly, but males do.

There's also a type of this moth that lives in mountains, south of the main Arctic area.

Discovering the Arctic Woolly Bear Moth

This moth was probably first found on June 16, 1832. It was discovered on the beach of Fury Bay, Somerset Island in northern Nunavut, Canada. The crew of an Arctic expedition led by John Ross found it while looking for the Northwest Passage.

Later, in 1870, more moths were found in northern Greenland. This happened during the Second German North Polar Expedition. Scientists like Alexander von Homeyer and Maximilian Ferdinand Wocke studied these moths. They realized it was a new species, but it was similar to another moth called Gynaephora rossii.

At first, people thought G. groenlandica only lived in the High Arctic. But in 2013, two groups of these moths were found in the mountains of southwest Yukon, Canada. This was 900 km (about 560 miles) south of where they were known to live! These new groups were different enough to be called a new subspecies (a type of the same species). It was named G. groenlandica beringiana.

In the 1980s, moths were also found on Wrangel Island, Russia. These were first thought to be a new species, but later they were identified as G. groenlandica. They are now known as G. groenlandica kusnezovi.

Here are the different types (subspecies) of the Arctic woolly bear moth:

• G. groenlandica groenlandica (the original Arctic type)
• G. groenlandica beringiana (the mountain type from Yukon)
• G. groenlandica kusnezovi (the type from Wrangel Island, Russia)

Even though G. groenlandica and G. rossii are similar, they cannot have babies together. They live in the same areas in parts of Canada and Wrangel Island, but they stay separate species.

What the Arctic Woolly Bear Moth Looks Like

The caterpillars of G. groenlandica are quite large, weighing about 300 mg. They are covered in thick, soft hair. Their color is usually tan-brown, but it can vary. They have a special tuft of hair on their eighth body segment. Their hairs are smooth, unlike the feathery hairs of their close relative, G. rossii.

You can also tell them apart by their wings. G. groenlandica moths do not have a wide, dark band on the edge of their back wings, which G. rossii does. Generally, G. rossii has more patterns on its wings than G. groenlandica.

The eggs of this moth are about 1.6mm in size.

The cocoons (the silky cases they build before becoming moths) of G. groenlandica have two layers. There's a pocket of air between these layers, which is different from the single-layered cocoons of G. rossii.

Where Arctic Woolly Bear Moths Live

The main type of Arctic woolly bear moth lives in the High Arctic. This includes Greenland and the Canadian Arctic Archipelago, like Ellesmere Island. They are found above about 70°N latitude. This makes them one of the most northern insects in the world! They live as far north as Ward Hunt Island in Canada.

The new subspecies, G. groenlandica beringiana, was found in 2013. It lives south of the Arctic Circle in the mountains of southwest Yukon. This is 900km (about 560 miles) south of where the moths were known to live before. The other subspecies, G. groenlandica kusnezovi, has only been found on Wrangel Island, Russia, as of 2015.

Their Home and How They Survive

G. groenlandica is very good at living in the extremely cold conditions of the High Arctic.

Scientists found that when G. groenlandica caterpillars are in their deep sleep (diapause), they choose specific spots to hide. They often attach their winter homes, called hibernacula, to the bottom of rocks. They prefer the side of rocks that is sheltered from the wind. This suggests that wind direction helps them choose where to spend the winter.

When kept in labs, these caterpillars have also been seen attaching themselves to dead leaves of the Salix arctica (Arctic willow) during their sleep period.

How Far They Travel

The G. groenlandica caterpillar can move several meters (a few yards) each day. They do this mainly to find good food. Scientists compared caterpillars that were moved between different Salix arctica plants with those that stayed on one plant. The caterpillars that moved ate more and grew faster. This shows that finding high-quality food is a big reason why these caterpillars move between plants.

What They Eat

Salix arctica, the Arctic willow, is the larva's primary food plant.

G. groenlandica spends most of its life as a caterpillar. So, food is super important for them to grow. The Salix arctica, or Arctic willow, is their main food source. The caterpillars might also eat other plants, like the flowers of Saxifraga oppositifolia or old leaves of Dryas integrifolia. However, in the High Arctic, less than 3% of caterpillars choose these other plants. The moths living in the mountains of southwest Yukon (G. g. beringiana) eat a wider variety of plants and less Arctic willow.

Caterpillars rarely eat the flower clusters of the Arctic willow. But they love its leaves. When they start eating in the spring, 97% of them eat the new leaf buds of this plant. Scientists have found that the caterpillars take nitrogen and potassium from the plant.

It seems the caterpillars only eat in June. This is when Arctic willow leaves have the most nutrients and sugars. The caterpillars eat less towards the end of June and into the summer. At this time, the leaves have fewer nutrients and become less tasty. This change in the leaves might be why the caterpillars stop eating as much.

The moth is adapted to a small temperature range. It can eat the most when temperatures are in the middle of its comfortable range.

Their Amazing Life Story

The life of G. groenlandica is shaped by the short, cold summers of the High Arctic. Because they only have a short time to grow each year, their whole life cycle takes about 7 years. In warmer mountain areas, their lifespan is much shorter, around 2–3 years.

Arctic woolly bear moths stay caterpillars for most of their lives. They are only adults for about 3–4 weeks in one summer. This long growth period is due to the cold temperatures and the food they eat. While they are caterpillars, G. groenlandica goes into a yearly winter sleep (diapause). This starts in late June or early July. About 10% of caterpillars die during this time in the wild.

How Their Life Cycle Works

On Ellesmere Island, female moths usually lay their eggs in a group inside or on their cocoon. Sometimes they lay them on the ground or on plants near the cocoon.

This moth spends most of its life as an older caterpillar. The early caterpillar stages and the adult stage only make up about 6% of its whole life. It's the older caterpillars that go through many yearly sleep periods. During this long stage (from the third to sixth caterpillar phases), G. groenlandica sheds its skin every year.

Caterpillars are only active for a short time after the snow melts. The High Arctic has a short growing season, only 45–70 days long. G. groenlandica stops eating by the end of June, before mid-summer. Caterpillars spend 95% of their active time either sunbathing, eating, or moving. Only 5% of their time is spent completely still. More specifically, about 60% of their time as caterpillars is spent sunbathing, 20% eating, and 15% moving.

In late June or early July, the caterpillars get ready for winter. They weave silky winter homes called hibernacula and enter their deep sleep (diapause). This usually happens when daytime temperatures are around 5-10 °C. In this sleep state, G. groenlandica can survive temperatures as low as -70 °C. On average, only about 13% of the population dies during winter.

All the stages of becoming a moth—like forming a pupa, coming out, mating, laying eggs, hatching, and shedding skin to become a second-stage caterpillar—happen within 3–4 weeks during one summer. Sometimes, coming out and reproducing can happen within just 24 hours.

Because adult moths live for such a short time, they are very hard to find in the wild.

Who They Interact With

The presence of these caterpillars eating plants in an area seems to be linked to how much the collared pika (Ochotona collaris) eats in southwest Yukon.

Their Predators

G. groenlandica has a special way to defend itself from bat sounds. When Arctic woolly bear moths hear bat-like ultrasound, male moths quickly turn around and fly away. They can react to the sound from up to 15-25 m (about 50-80 feet) away.

However, female moths have a weaker bat-sensing system. There are two main reasons for this. First, females usually don't fly, so they don't need this defense as much. Second, an ear system would take up space needed for their ovaries, and the cost of having good hearing might be too high compared to having fully working reproductive organs.

In the High Arctic, birds eat these moths. Small birds also eat their eggs. On Ellesmere Island, birds might even tear open the cocoons to get to the eggs inside.

Parasites That Attack Them

Many G. groenlandica caterpillars die because of parasitoids. These are insects that lay their eggs inside other insects. The main ones are the tachinid fly Exorista thula and the ichneumonid wasp Hyposoter diechmanni.

Exorista thula was found on Ellesmere Island in 2012. This fly lays one egg in a caterpillar. On the island, it killed about 20% of the third and fourth stage caterpillars. Even though it lives in the same area as the similar Gynaephora rossii moth, Exorista thula only attacks G. groenlandica. Another fly, Chetogena gelida, only attacks G. rossii. In general, more than two-thirds of Gynaephora caterpillars are killed by parasitoids. For G. groenlandica, over 50% die this way. The chance of being attacked by a parasitoid increases towards the end of the caterpillar's active period, which is when they are eating less.

The winter home (hibernaculum) where caterpillars spend most of their lives acts as a shield against these parasitoids.

How Their Bodies Work

Flight Abilities

While female G. groenlandica moths have full wings and can fly for a short time, they usually don't. But it's interesting that females of the more southern mountain subspecies often fly more.

Male moths, on the other hand, tend to fly high, fast, and in a zig-zag way during the day.

Controlling Body Temperature

The most active time for G. groenlandica is in June. This is when the High Arctic has the most sunlight (24 hours a day). However, temperatures are still very low. Ground temperatures in June are usually less than 10 °C (50°F).

At this time, caterpillars that are eating have similar body temperatures to those shedding skin or spinning cocoons. But caterpillars that are "basking" (sunbathing) have higher temperatures. G. groenlandica caterpillars spend about 60% of their time basking, even when they are forming their pupa. Basking means the caterpillar positions its body to get the most sun and avoid wind. They follow the sun's angle to absorb as much sunlight as possible. By basking, G. groenlandica caterpillars can raise their body temperature by up to 20 °C (68°F). Their highest body temperature is usually around 30 °C (86°F). This peak temperature is usually only reached when they lie in the midday sun, surrounded by snow, on a calm day.

Sunlight helps caterpillars grow. So, basking can make them develop faster. When scientists compared growth rates at 5, 10, and 30 °C, they found that growth was slowest at 5 °C and fastest at 30 °C. As their body temperature increases from basking, their metabolism (how fast their body uses energy) increases a lot. This was true even when caterpillars were hungry or seemed inactive.

Caterpillars that are eating usually have lower body temperatures than those basking. So, they tend to eat when temperatures are highest. They bask when they can't reach the higher temperatures (more than 5-10 °C) needed for activity. It's thought that without basking in the 24-hour sunlight of High Arctic summers, caterpillars would rarely get warm enough to grow (above ~5 °C). This might explain why the Arctic woolly bear moth has short eating periods during peak sunlight, followed by longer periods of basking and digesting.

In early to mid-June, how much they eat and the rising temperature greatly affect their metabolism. Later in the active season, their metabolism becomes less sensitive to temperature. Energy from food is saved.

Changes in metabolism and body temperature also affect how much oxygen they use. Oxygen use was much lower when caterpillar body temperatures were below 10 °C. Low oxygen use was also seen in inactive caterpillars. In contrast, it was higher for caterpillars that were moving or hungry, even higher for digesting caterpillars, and highest for eating caterpillars.

Digesting Food

Caterpillars often sunbathe for about five hours after eating before moving to a new spot. The higher body temperature from basking helps their gut enzymes work better, which means they digest food faster. G. groenlandica can turn the food they eat into energy more efficiently than most other moth and butterfly species.

Their Winter Sleep (Diapause)

G. groenlandica goes through a period of winter diapause. During this time, it stays dormant (asleep) inside its hibernaculum. In this state, it can survive temperatures as low as -70 °C (-94°F).

Being inside a hibernaculum during diapause helps in several ways:

• It protects them from parasitoids (insects that lay eggs inside them).
• It helps them avoid eating their main food source, Salix arctica, when its nutrients are low.
• It helps them produce "antifreeze" chemicals that protect their cells from the cold.
• It helps them save energy.

These cocoons are made of silk and have two layers, with the caterpillar's hairs woven in. In a 1995 study, 81% of caterpillars in a controlled environment in the High Arctic built hibernacula.

During their active season, caterpillars face the sun. Each one spins its hibernaculum over a 24-hour period. They usually form their pupa with their head facing south. This cocoon helps the caterpillars gather heat more effectively.

G. groenlandica often attaches its hibernacula to the base of rocks. In labs, they have also been seen attaching themselves to dead leaves of Salix arctica. In the 1995 study, more hibernacula were found on other plants like Dryas integrifolia (mountain avens) and Cassiope tetragona (Arctic white heather) than on their main food plant, S. arctica.

Almost half of the caterpillars that spun hibernacula did so with other caterpillars, forming shared cocoons. Sometimes, three or more caterpillars shared a cocoon, but usually, it was two. More shared cocoons happened when there were fewer caterpillars in a cage.

As temperatures drop in the late Arctic summer, caterpillars start making special chemicals called cryoprotective compounds, like glycerol. These "antifreezes" protect their cells from freezing. While they still get energy from stored sugar when frozen, their metabolism drops so low that it almost stops. This causes their deep sleep. Their body functions can fully restart in the spring after just a few hours of activity.

Why They Are Important for Conservation

At warmer temperatures, Arctic moth caterpillars generally breathe faster and grow slower. They also tend to change their diets to more nutrient-rich foods in warmer places. For example, how much G. groenlandica eats its main food, S. arctica, changes when temperatures are higher. This means that the moth's diet can change depending on the environment.

This also suggests that an increase in temperature due to global warming could greatly affect the behavior of Arctic insects like G. groenlandica. It could also affect how much they eat their food sources. So, G. groenlandica could be an important species to study for future research on climate change.

Images for kids

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  Salix arctica, the Arctic willow, is the larva's primary food plant.