Caribou Bot Fly vs Secondary Screwworm Fly

Side-by-side species comparison

Attribute	Caribou Bot Fly	Secondary Screwworm Fly
Scientific Name	Cephenemyia jellisoni	Cochliomyia macellaria
Order	Diptera	Diptera
Family	Oestridae	Calliphoridae
Size	12-16 mm	8-12 mm
Habitat	Heathland	Farmland
Diet	Omnivores	Carrion Feeders
Regions	Alaska, northern Canada, Yukon, Northwest Territories	North America, South America
Conservation	Least Concern	Least Concern

Caribou Bot Fly

A robust, furry fly that parasitizes caribou and deer in North America. Like its Eurasian relative, it deposits larvae near the nostrils of its host. Adults have vestigial mouthparts and survive entirely on stored energy.

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Did You Know?

Infected caribou may sneeze violently to expel mature bot fly larvae from their nasal passages before the larvae pupate in the soil.

Secondary Screwworm Fly

A blow fly that breeds in carrion and occasionally infests wounds in livestock. It is widely used in forensic studies in the Americas.

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Did You Know?

Unlike the primary screwworm, it only feeds on dead tissue rather than living flesh.