Mountain Dance Fly vs North American Alderfly

Side-by-side species comparison

Attribute Mountain Dance Fly North American Alderfly
Scientific Name Empis pennipes Sialis infumata
Order Diptera Megaloptera
Family Empididae Sialidae
Size 5-8 mm body length 15-20 mm wingspan
Habitat Rivers & Streams Rivers & Streams
Diet Predators Predators
Regions Europe, Alps, Scandinavia Eastern North America
Conservation Least Concern Least Concern

Mountain Dance Fly

A predatory fly with feathery leg fringes used in aerial mating displays. Males offer prey gifts wrapped in silk to females during courtship.

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Did You Know?

Males with the most elaborate feathered legs are preferred by females during mating swarms.

North American Alderfly

A small, dark-winged alderfly common near ponds and slow streams across eastern North America. Adults are clumsy fliers often found resting on streamside plants.

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Did You Know?

Larvae spend one to two years burrowing in pond mud before emerging for a brief adult life of just days.