UNITED NEWS INTERNATIONAL (UNI) — Slimy, predatory creatures are invading France and experts say they’ve been doing so for years.

They’re called hammerhead flatworms and they can measure up to 45 centimeters long.

These long, skinny worms are concerning researchers because they don’t belong in Metropolitan France.

They also eat native earthworm populations.

An amateur naturalist first alerted experts to the invasion.

Pierre Gros started taking pictures of the worms when he found them in his garden outside Paris.

He sent the pictures to Jean-Lou Justine at the National Museum of Natural History in Paris. 

According to a study published May 24 in the journal PeerJ, these hammerhead worms are native to tropical Asia.

Upon further investigation, researchers uncovered reports from French citizens who noticed the flatworms as early as 1999.

It appears the hammerhead flatworm is in France to stay.

Justine told The Washington Post, “They are infesting gardens year after year after year.”