Petroleum Fly vs Hairy Whirligig Beetle

Side-by-side species comparison

Attribute Petroleum Fly Hairy Whirligig Beetle
Scientific Name Helaeomyia petrolei Orectochilus villosus
Order Diptera Coleoptera
Family Ephydridae Gyrinidae
Size 5 mm 5-7 mm
Habitat Underground Rivers & Streams
Diet Omnivores Omnivores
Regions North America Europe
Conservation Least Concern Least Concern

Petroleum Fly

The only insect whose larvae develop in crude petroleum. Found in natural oil seeps in California, including the La Brea Tar Pits. Larvae eat insects trapped in the oil.

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Did You Know?

This is the only animal on Earth that develops in crude oil — a substance toxic to virtually all other life. Its larvae swim through petroleum and breathe through snorkel-like tubes.

Hairy Whirligig Beetle

A nocturnal whirligig beetle covered in fine golden hairs that trap air underwater. Unlike other whirligigs it hides under stones by day.

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Did You Know?

It is the only European whirligig beetle that is primarily nocturnal rather than diurnal.