Compsilura concinnata facts for kids
Quick facts for kids Compsilura concinnata |
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Compsilura
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concinnata
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Compsilura concinnata is a type of fly that is a parasitoid. This means its young live inside another insect, called a host, and eventually kill it. This fly originally comes from Europe. In 1906, scientists brought it to North America to solve a big problem: the invasive spongy moth. The spongy moth caterpillars were eating the leaves off trees in forests.
The plan was for the fly to attack the spongy moth caterpillars. However, the fly is not a picky eater. It is a "generalist," which means it attacks many different kinds of insects. It has been found to attack over 200 different species, including many native North American butterflies and moths. Some of these include the beautiful Monarch butterfly, the giant cecropia moth, and the glowing Luna moth. This has created new problems for the local wildlife.
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What Does This Fly Look Like?
The adult Compsilura concinnata looks a lot like a common housefly. It grows to be about 7.5 millimeters long. It has a white face and four black stripes on its thorax (the middle part of its body).
Like other flies, it goes through several stages in its life.
- Larva: The young fly, or larva, is a creamy-colored maggot. It has black hooks for a mouth.
- Pupa: The pupa is the stage where the larva transforms into an adult fly. It is a brown, oval-shaped case about 6.5 millimeters long.
The Life Cycle of a Parasitoid Fly
This fly has a fascinating and somewhat scary life cycle. It can have three to four generations in a single year, and an adult fly lives for about one to three weeks.
How It Reproduces
The mother fly has a special way of giving birth. Instead of laying eggs, she keeps the eggs inside her body until they hatch. She then injects a tiny, live larva directly into a host, which is usually a caterpillar.
Here is how the process works:
- The female fly finds a suitable caterpillar.
- She uses a sharp, piercing part on her body to make a small hole in the caterpillar's skin.
- She injects one of her larvae inside the caterpillar. A single female can do this to about 100 different caterpillars.
Growing Up Inside a Host
Once inside, the fly larva begins to feed on the caterpillar from the inside out. It stays inside its host for about 10 to 17 days. The caterpillar is still alive during this time.
When the larva is fully grown, it emerges from the caterpillar's body. This kills the host. The larva then forms a hard, reddish-brown case around itself called a puparium. Inside this case, it transforms into an adult fly.
An Introduced Species with Unexpected Results
Bringing Compsilura concinnata to North America is an example of biological control gone wrong. The goal was to control one pest, but the fly ended up harming many other insects.
Why It Became a Problem
There are a few key reasons why this fly has had such a negative impact on native butterflies and moths.
- Different Life Cycles: The fly has 3-4 generations a year. Its main target, the spongy moth, only has one generation a year. This means the fly is always looking for hosts, even when spongy moth caterpillars aren't around.
- Winter Survival: The spongy moth survives the winter as eggs. But the fly needs a live caterpillar to live inside during the winter. So, it finds other native caterpillars that are active during the colder months.
- Not a Picky Eater: The fly is a generalist, meaning it will attack many different species. It doesn't just stick to the spongy moth. This has put over 150 native North American species at risk.
Is It Effective Against Spongy Moths?
Even though it was brought to North America to fight the spongy moth, it's not very good at it. Studies show that during a large outbreak of spongy moths, the fly attacks less than 5% of them. It is more successful when the moth population is smaller. Because it attacks so many other insects, it is not considered an effective or safe way to control spongy moths today.
This story is an important lesson for scientists. It shows that introducing a new species into an ecosystem can have surprising and harmful effects that are difficult to predict.
