Water Scavenger Beetle vs Knapweed Gall Weevil

Side-by-side species comparison

Attribute Water Scavenger Beetle Knapweed Gall Weevil
Scientific Name Hydrophilus piceus Bangasternus fausti
Order Coleoptera Coleoptera
Family Hydrophilidae Curculionidae
Size 34-48 mm 4-6 mm
Habitat Ponds & Lakes Grasslands
Diet Herbivores Gall Makers
Regions Europe, Asia Europe, Central Asia
Conservation Near Threatened Least Concern

Water Scavenger Beetle

One of the largest European water beetles, with a glossy black, boat-shaped body. Despite its name, it is largely herbivorous as an adult.

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Did You Know?

It carries air under its body in a silvery film, giving it a shimmering appearance underwater.

Knapweed Gall Weevil

A weevil that induces galls in knapweed flower heads. Larvae develop inside the enlarged flower buds. Used in biological control of invasive knapweeds in North America.

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Did You Know?

Released in North America as biocontrol for invasive spotted knapweed, which costs ranchers millions annually.