Lyperobius huttoni facts for kids
Quick facts for kids Lyperobius huttoni |
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| Illustration by Des Helmore | |
| Scientific classification | |
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Molytinae
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| Genus: |
Lyperobius
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L. huttoni
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| Lyperobius huttoni Pascoe, 1876
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Lyperobius huttoni is a special type of weevil found only in New Zealand. It's often called Hutton's speargrass weevil or just speargrass weevil. This insect lives in the high mountains of the South Island. You can also find it near the coast around Wellington.
This weevil has a very specific diet. It eats only speargrass plants (Aciphylla). Because of threats, some weevils from Wellington have been moved to Mana Island. This island is a safe place without many predators.
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Discovering This Weevil
This weevil was first officially described in 1876. A scientist named Francis Pascoe gave it its scientific name. He based his description on weevils collected by Frederick Hutton. Hutton found these weevils near Nelson. He found them on a type of speargrass called Aciphylla colensoi. Pascoe named the weevil huttoni to honor Frederick Hutton. The original specimen used for the description is kept in a museum in London.
What Does It Look Like?
This weevil is dark in color. It is about 2 centimeters (almost an inch) long. It has a short, thick snout, which is called a rostrum. It's hard to tell male and female weevils apart just by looking. Females are usually a little bigger. They also have a slightly larger and rounder part on their belly.
Another scientist, George Hudson, compared this weevil to a similar one. He said L. huttoni is larger. It has a shorter and wider snout. Its wing covers have six rows of deep, dot-like marks. The weevil is mostly black with a hint of reddish color. It has very little hair or fuzz on its body.
Where Does It Live?
Lyperobius huttoni lives in high-altitude areas. These include herbfields and tussock grasslands. You can find them in the eastern South Island. Their range goes from the Black Birch range in Marlborough down to the Hunters Hills in South Canterbury.
A group of these weevils was found in 1917 near the Wellington south coast. This was a surprise because they usually live in the mountains. But in Wellington, their host plant, Aciphylla squarrosa, grows on exposed coastal cliffs. This means it can be found almost at sea level.
This weevil is the only Lyperobius species found on both the North Island and South Island. Scientists think they might have crossed the Cook Strait long ago. This could have happened during the last ice age. At that time, sea levels were much lower. Or, they might have floated across on natural rafts of debris.
Some weevils from the Wellington group have been moved to Mana Island. This helps protect them.
Weevil Behavior and Life Cycle
L. huttoni eats specific types of speargrass. These include Aciphylla squarrosa, A. colensoi, and A. aurea. Adult weevils are active during the day. You can best find them on plant leaves on warm, sunny, calm days. They feed on the leaves and flower stalks of the speargrass. When they eat, they leave small notches on the edges of the leaves. Sometimes, they even eat through the entire leaf.
The baby weevils, called larvae, live underground. They dig into the soil and eat the main root of the Aciphylla plant. You can also find them in the dead leaves around the plant's base. If you see dead or dying speargrass plants, or deep oval notches on the leaf stalks, it might be a sign of these larvae.
A weevil spends about a year as a larva. Then, it builds a special chamber in the soil. Inside this chamber, it changes into a pupa. This pupa stage lasts for about two weeks. After changing, the adult weevil can stay in its chamber for up to eight months before coming out. Once it emerges, an adult weevil can live for over two years.
Weevil Health
Scientists once tried to breed L. huttoni in captivity. During this research, they found that the weevil can get sick from a type of fungus. This fungus belongs to the genus Beauvaria. This fungus was a major reason why many weevils died during the study.
Protecting the Weevil
This weevil is a protected animal in New Zealand. This means it's against the law to harm them. They are flightless, meaning they cannot fly. They also move slowly. This makes them easy targets for predators like mice and rats. Their food plants, the speargrass, are also at risk. Animals like sheep, pigs, and goats can eat too much of the plants. For example, one group of weevils in Wellington disappeared. Their entire home was destroyed when it was turned into a quarry.
In Marlborough, the weevil population seems stable. But in Canterbury, things are tougher. Rodents eat them, and their habitat is being destroyed. This has caused their numbers to go down.
The Wellington population used to spread across a larger area. By the 1980s, it was almost gone. From 2001 to 2004, people tried to breed them in captivity. But many adult weevils died, and the larvae didn't survive. So, no new adults could be released. By 2006, the Department of Conservation (DOC) thought there were fewer than 150 adult weevils left in Wellington.
To help them, DOC moved 40 adult weevils to nearby Mana Island. This happened in the summer of 2006–2007. In 2015, a survey found many signs that the weevils were feeding well on Mana Island. One weevil was even seen far from where it was released. This shows the move was a success!
