
	Description
	The eyes are green, sometimes with a little red. The abdomen is pale gray with a distinct, sharply delineated black stripe – “tiger stripe” – marking on the upper side of each segment.

	Size
	Total length: 1″ to 1¼″

	Similar Species
	Other giant robber flies (genus Promachus) have dark markings on the upper side of the abdomen. Only P. vertebratus has a distinct, sharply delineated black stripe – “tiger stripe” – marking on the upper portion of each segment.


	Habitat
	Prairies, disturbed areas.


	Biology
	Season
	Mid-July to early September

	Behavior
	It makes a loud buzzing noise as it flies.

	Life Cycle


	Larva Food


	Adult Food


	Taxonomy
	Order	Diptera (flies)
	Suborder	Brachycera
	Infraorder	Asilomorpha (Orthorrhapha)
	Superfamily	Asiloidea
	Family	Asilidae (robber flies)
	Subfamily	Asilinae
	Tribe	Apocleini
	Genus	Promachus (giant robber flies)

	Synonyms
	Asilus vertebratus

	Common Names
	This species has no common name. The common name of the genus Promachus is giant robber flies, and it is applied here for convenience.


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	Dan W. Andree

	Robber Fly.... It was depositing eggs in a dried cone flower at Twin Valley Prairie on Aug. 18, 2022

	? on Green-eyed Robber Fly... I noticed what I believe to be a Green-eyed Robber Fly motioning it tail end in and out of this Coneflower. I believe it was depositing eggs in it. It would poke it in and out several times and I filmed it doing so.





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	Other Videos


	Giant Robber Fly (Asilidae: Promachus vertebratus) Mating Carl Barrentine

	About Uploaded on Aug 13, 2010 Photographed at the Turtle River State Park, North Dakota (11 August 2010). Thank you to Herschel Raney (@Bugguide.net) for identifying this specimen!

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Dan W. Andree 8/18/2022	Location: Twin Valley Prairie SNA It was depositing eggs in a dried cone flower at Twin Valley Prairie on Aug. 18, 2022



Dan W. Andree 8/11/2019	Location: Frenchman’s Bluff SNA, Norman Co. Mn. I noticed what I believe to be a Green-eyed Robber Fly motioning it tail end in and out of this Coneflower. I believe it was depositing eggs in it. It would poke it in and out several times and I filmed it doing so.



Kyle, PLM 8/30/2017	Location: Pope County Many many of these zipping around as we are harvesting stiff sunflower. They are landing on the sunflower and either pollinating or laying eggs...not sure, but they sure like stiff sunflower.



MinnesotaSeasons.com Sightings

Mound Spring Prairie SNA, North Unit

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Created 2/15/2012

Last Updated:

giant robber fly