bumble bee mimic robber fly

(Laphria thoracica)

Conservation Status

IUCN Red List

not listed

bumble bee mimic robber fly (Laphria thoracica)


not listed


not listed




Late May through July


Woodland edges


Total Length: about ¾



Laphria thoracica is a large bumble bee mimic robber fly. It occurs in the United States from the northeast to the Midwest and south to Tennessee, and in adjacent Canadian provinces. There are at least 33 Laphria species in the eastern United States. Laphria thoracica is probably the most common. It is uncommon in Minnesota, where it is at the western extent of its range.

Adults are robust, very hairy, and about ¾ long. The thorax and abdomen are partially covered with long yellow hairs making it resemble a bumble bee. It is a mimic of common eastern bumble bee (Bombus impatiens), half-black bumble bee (B. vagans), and lemon cuckoo bumble bee (B. citrinus).

The thorax is stout and black. It is densely covered with long, erect, yellow hairs except for a small, round, black, bare spot in the middle. The yellow hairs extend in an arc from the front of the thorax to the side below the wing base.

The abdomen widens beyond the middle. The amount of yellow on the abdomen varies. On the female, the abdomen is entirely black. On the male, segment 1 is always black, and segments 2, 3, and 4 are often completely or partially covered with long yellow hairs.

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. The upper face is covered with long, erect hairs that may be mostly yellow, mostly black, or entirely black. There is a dense mustache of long stiff bristles (mystax) on the face between the compound eyes at the lower margin, and a cluster of forward-directed bristles (a “beard”) on the lower part of the face. The mystax and beard are mostly black with a few scattered yellow hairs. The antennae have 3 segments. The third segment is elongated.

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

On the wing, the first and second radius veins (R1 and R2+3) join before the end of R1 creating a closed cell that does not reach the margin.



Larval Food

Beetle larvae

Adult Food

Bees and beetles

Life Cycle

Larvae are borers in moist, dead wood.


It buzzes loudly when it flies. It captures its prey in flight. It uses its sharp proboscis to pierce its prey, inject enzymes which liquefy the prey’s organs, and suck out the resulting liquid.

It can deliver a painful bite when handled.

Distribution Distribution Map  

Sources: 7, 24, 27, 29, 30.


No Common Name
Few of the North American Laphria species have a common name. The common name for the genus is bee-like robber fly. Laphria thoracica is one of several species known for being a bumble bee mimic, so “bumble bee mimic robber fly” will stand in for the common name.



Diptera (gnats, mosquitoes, true flies)



Brachycera (circular-seamed flies, mouches muscoïdes, muscoid flies, short-horned flies)









Asilidae (robber flies)








Dasyllis thoracica

Laphria alcanor

Laphria fulvithorax


no common name









On insects in the family Asilidae (robber flies): a dense mustache of stiff bristles on the face.



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



The last two to five subdivisions of an insect’s leg, attached to the tibia; the foot. Plural: tarsi.







Visitor Photos

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Alfredo Colon

  bumble bee mimic robber fly (Laphria thoracica)   bumble bee mimic robber fly (Laphria thoracica)


MinnesotaSeasons.com Photos

  bumble bee mimic robber fly (Laphria thoracica)   bumble bee mimic robber fly (Laphria thoracica)
  bumble bee mimic robber fly (Laphria thoracica)    





  Laphria thoracica
Steve Collins
  Laphria thoracica  




Visitor Videos

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Other Videos

  Bee-like Robber Fly (Asilidae: Laphria thoracica) Anterior View
Carl Barrentine

Published on Jun 12, 2012

Photographed at the Turtle River State Park, North Dakota (12 June 1012). This species of robber fly is a good mimic of this local bumble bee: https://www.youtube.com/watch?v=zbD04dxYpTM

  Bee-like Robber Fly (Asilidae: Laphria thoracica)
Carl Barrentine

Published on Sep 13, 2009

Photographed at the Kellys Slough NWR, North Dakota (13 September 2009).

  Predators: The Watchful Robber Fly
Carl Barrentine

Published on Jul 12, 2015

This short film introduces a robber fly that mimics a bumble bee (Family Asilidae), Laphria thoracica. This very large raptor-like fly is known to feed on honey bees. Filmed at Grand Forks, North Dakota (09 July 2015). A Lucretius Production.





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Alfredo Colon

Location: Woodbury, Minnesota

bumble bee mimic robber fly (Laphria thoracica)


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