Yellow May Dun vs Giant Silk Moth

Side-by-side species comparison

Attribute Yellow May Dun Giant Silk Moth
Scientific Name Heptagenia sulphurea Hyalophora euryalus
Order Ephemeroptera Lepidoptera
Family Heptageniidae Saturniidae
Size 10-15 mm 90-130 mm
Habitat Rivers & Streams Farmland
Diet Omnivores Omnivores
Regions Europe Western North America, from British Columbia to Baja California
Conservation Least Concern Least Concern

Yellow May Dun

A bright sulfur-yellow mayfly common across European rivers during early summer. Its flat nymphs are adapted to fast-flowing water on stony substrates.

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Did You Know?

The striking yellow color of this mayfly makes it one of the most easily recognizable species on European rivers.

Giant Silk Moth

A large western North American silk moth with reddish-brown wings featuring bold white crescent markings and a red-and-white banded body. It is the Pacific coast counterpart of the cecropia moth.

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Did You Know?

Hyalophora euryalus can hybridize with the cecropia moth where their ranges overlap, producing fertile offspring in a zone of intergradation.