Holcocephala is a genus of small robber flies called gnat ogres. It occurs in North America, Central America, and South America. In the United States, it occurs east of the Great Plains. It also occurs in southern Quebec and Ontario.

There are at least 40 Holcocephala species worldwide, 3 species in North America north of Mexico, and 2 species in Minnesota.

Adults are active from June to September. They are found in meadows, fields, wetlands, and woodlands, and at the margins of streams. When foraging, they perch mostly at the tips of dead twigs but also at the tips of vegetation. They are most active in the morning.

Photo by Alfredo Colon

Description

Gnat ogres are soft bodied and small, ⅛″ to ⅜″ (4.0 to 9.4 mm) in length. The head is short but very wide. The eyes are very large, and they are widely spaced, giving the insect a goggle-eyed appearance. The antennae are short, no longer than the head.

The thorax is prominent and high. It is steeply arched in front and at the rear. It is densely covered with short, velvety hairs that completely hide the underlying color. It is pale with a broad, dark, longitudinal stripe in the middle and two or three dark brown spots on each side (subdorsal).

The abdomen is short, broad at the base, and tapered toward the tip.

The wings are longer than the abdomen. They are blackish, mostly dark, pale on the outer third. They are held over the body when at rest. Every cell near the wing tip is broadly open.

The legs are long.


Distribution
		Sources 24, 29, 30, 82, 83.
5/26/2024


Taxonomy
Order	Diptera (flies)
Suborder	Brachycera
Infraorder	Cyclorrhapha
Superfamily	Asiloidea
Family	Asilidae (robber flies)
Subfamily	Trigonomiminae
Tribe	Trigonomimini

Most sources place the genus Holcocephala in the tribe Damalini. However, a handful of sources reject that name as a junior synonym of Xenomyzini, following Article 40.1 of the ICZN rules. The name Trigonomimini is older and therefore has precedence. The short list of sources that place Holcocephala in the tribe Trigonomimini includes Robber Flies of the World, AsilidaeData, The National Museum of Natural History at the Smithsonian Institution, and iNaturalist.

Subordinate Taxa
Holcocephala abdominalis Holcocephala affinis Holcocephala agalla Holcocephala analis Holcocephala bechyneorum Holcocephala calva Holcocephala coriacea Holcocephala curvicosta Holcocephala deltoidea Holcocephala dimidiata Holcocephala divisa Holcocephala fernandezi Holcocephala fimbriata Holcocephala fusca Holcocephala indigena Holcocephala inornata Holcocephala luteipes Holcocephala macula Holcocephala matteii Holcocephala minuta Holcocephala mogiana Holcocephala monticola Holcocephala nigrita Holcocephala nitida Holcocephala nodosipes Holcocephala obscuripennis Holcocephala oculata Holcocephala pardalina Holcocephala pectinata Holcocephala pennipes Holcocephala peruviana Holcocephala rufithorax Holcocephala scopifer Holcocephala spinipes Holcocephala stylata Holcocephala tijucana Holcocephala uruguayensis Holcocephala vallestris Holcocephala vicina Holcocephala vittata

Synonyms
Helcocephala (misspelling) Holocephala (misspelling)

Common Names
gnat ogres


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Alfredo Colon


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Robber fly eating insects & grooming | Holcocephala
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Aug 27, 2020

Gnat-Ogre Robber Fly (Holcocephala sp) cleaning
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Jul 25, 2019

Gnat-Ogre Robber Fly (Holcocephala sp) cleaning

(Walnut Woods Metro Park, Franklin County, Ohio, USA, 23JUL2019, wwwBUGS.org)

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Jul 4, 2020

ROBBER FLY, Holcocephala feediing on beetle. McClaughery Springs FP, IL. 9/15/2019 1305750

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