bee-mimic robber fly

(Laphria index)

Conservation Status
bee-mimic robber fly (Laphria index)
Photo by Alfredo Colon
  IUCN Red List

not listed

 
  NatureServe

not listed

 
  Minnesota

not listed

 
           
           
           
 
Description
 
 

Laphria index is a small to medium-sized bee-mimic robber fly. It occurs in the United States from the northeast to the Midwest, south to Virginia and Missouri, and in adjacent Canadian provinces. It is uncommon in Minnesota.

Adults are dark, slender, and ½ to 11 16 (13 to 18 mm) long.

There are two large compound eyes and three small simple eyes (ocelli). The compound eyes extend above the level of the top of the head (vertex), making the head appear hollowed out between the eyes when viewed from the front. The ocelli are arranged in a triangle on a prominent rounded projection (tubercle) in the middle of the head between the compound eyes. There is a dense mustache of long, stiff, black bristles (mystax) on the face immediately above the mouth. The antennae have 3 segments. The third segment is elongated.

The thorax is black with a narrow triangle of pale to reddish-gold hairs on the upper (dorsal) surface. The triangle is widest at the rear, about as wide as the triangular plate between the thorax and abdomen (scutellum). It narrows rapidly to at least the middle of the thorax, and fades at the tip. The hairs are iridescent and the color varies with the angle of the light. The rest of the thorax is covered with longer whitish hairs and shorter black hairs. The scutellum is covered with paler hairs and has a white bristles on the margin. The small, knob-like structures on each side of the thorax (halteres) are yellow.

The abdomen is long, slender, and black, and has six segments. The first two segments are black with white hairs on the side. Segments 3 through 6 are densely covered with orangish-gold hairs. On the male, at the rear margin of segment six, there are two black, well-defined projections. The genital bulb at the tip of the abdomen is black and very large.

The wings are clear. They are dark smoky brown at the tip, becoming paler at the base. The first and second branches of the radial sector vein (R1 and R2+3) join before the end of R1 creating a closed cell that does not reach the margin.

The legs are stout and black. They are covered with long gray and black hairs. The last part of the leg (tarsus), corresponding to the foot, has five segments. The last segment has 2 pads.

 
     
 

Size

 
 

Total length: ½ to 11 16

 
     
 

Similar Species

 
 

Bee-mimic robber fly (Laphria ithypyga) is very similar in appearance. On the male, the genital bulb is “substantially smaller”. At the tip of the abdomen there is just a single small projection. Neither of these characteristics is visible on most photos. The female “appears to be more robust”, and the golden triangle on her thorax “more conspicuous” (BugGuide.net). Based on the recorded sightings, this species is much less common. It has not been recorded in Minnesota, though CCESR does have it on their state insect checklist as Choerades ithypygus.

 
     
 
Habitat
 
 

Woodland edges and openings

 
     
 
Biology
 
 

Season

 
 

June through mid-August

 
     
 

Behavior

 
 

 

 
     
 

Life Cycle

 
 

 

 
     
 

Larva Food

 
 

 

 
     
 

Adult Food

 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 24, 27, 29, 30, 82.

 
  10/4/2022      
         
 

Occurrence

 
 

 

 
         
 
Taxonomy
 
 

Order

Diptera (flies)  
 

Suborder

Brachycera  
 

Infraorder

Cyclorrhapha  
 

Superfamily

Asiloidea  
 

Family

Asilidae (robber flies)  
 

Subfamily

Laphriinae  
 

Tribe

Laphriini  
 

Genus

Laphria (bee-mimic robber flies)  
  no taxa bee-mimic robber flies (Laphria index complex)  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

Few of the North American Laphria species have a common name. One common name for the genus is bee-mimic robber fly, and it is applied here for convenience.

 

 

 

 

 

 

 

Glossary

Halteres

In flies: a pair of knob-like structures on the thorax representing hind wings that are used for balance.

 

Mystax

On flies, especially in the family Asilidae, a patch of bristles or hairs (mustache) immediately above the mouth.

 

Ocellus

Simple eye; an eye with a single lens. Plural: ocelli.

 

Scutellum

The exoskeletal plate covering the rearward (posterior) part of the middle segment of the thorax in some insects. In Coleoptera, Hemiptera, and Homoptera, the dorsal, often triangular plate behind the pronotum and between the bases of the front wings. In Diptera, the exoskeletal plate between the abdomen and the thorax.

 

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.

 

 

 

 

 

 
 
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Alfredo Colon

 
 

An Awesome Robberfly

 
    bee-mimic robber fly (Laphria index)      
           
 
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Other Videos
 
  Robber Fly (Asilidae: Laphria index) Male, Close-up
Carl Barrentine
 
   
 
About

Published on May 29, 2012

Photographed at the Turtle River State Park, North Dakota (29 May 2012). Thank you to Herschel Raney (@Bugguide.net) for confirming the identity and for suggesting the sex of this specimen!

 
  Laphria index ORANGE ROBBER FLY
Rob Curtis
 
   
 
About

Published on Nov 19, 2017

Laphria index ORANGE ROBBER FLY

 
  Robber Fly (Asilidae: Laphria index/ithypyga complex) Female Feeding
Carl Barrentine
 
   
 
About

Published on Jun 24, 2012

Photographed at the Turtle River State Park, North Dakota (24 June 2012). Thank you to Tristan McKnight (@Bugguide.net) for determining the sex and probable identity of this specimen!

 

 

Camcorder

 
 
Visitor Sightings
 
           
 

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  Alfredo Colon
6/13/2018

Location: Woodbury, Minnesota

An Awesome Robberfly

bee-mimic robber fly (Laphria index)  
           
 
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