common eastern physocephala

(Physocephala tibialis)

Conservation Status
common eastern physocephala
Photo by Alfredo Colon
  IUCN Red List

not listed


not listed

NNR - Unranked


not listed


Common eastern physocephala is a medium-sized thick-headed fly. It is common in the United States from the east coast to the Midwest but mostly east of the Mississippi River. It is less common in Minnesota where it is at the western edge of its range.

At 7 16 to ½ long, it is a medium-sized fly but is relatively large for the genus Physocephala. With its thread-waisted body it strongly resembles a wasp, and like a wasp, it parasitizes living insects.

The head is bulbous and large, a little wider than the thorax. The top of the head (vertex) is dark brown or black. There is a narrow white line on the back of the head (occiput). There are two large compound eyes and no simple eyes (ocelli). The compound eyes are situated at the sides of the head and do not meet in the middle on either sex. The face is mostly white and prominently grooved. There is a black, fairly wide, sharply defined, T-shaped mark on the upper face (frons). The cheeks and facial grooves are black, and the facial keel is black, at least at the top. There is a very narrow silvery stripe on the face along the margin of the compound eye. The protruding mouthpart (proboscis) projects forward needle-like. It is long, straight (not elbowed), black, and conspicuously swollen at the base. The antennae have three segments. They are straight, black, and long, longer than the head, and project forward and up. The first segment is about the same length as the third. The second segment is as long as the first and third combined. The third segment is cone-shaped and has a slender, elongated process (style) at the tip.

The thorax is black and appears dusted whitish when viewed at an angle. The front angles (humeral spots) are narrow, black, and raised like shoulder pads. The balancing organs (halteres) are knob-like and yellow. The exoskeletal plate between the thorax and abdomen (scutellum) is dark brown or black.

The abdomen is black with a narrow band at the end (posterior) of each segment. The band is wider and white on segments one and two, narrower and yellowish-white on the remaining segments. The second segment and part of the third are very constricted (petiolate). Segments four through six have a white dusting above.

The legs are mostly black. The second segment (trochanter) and the base and tip of the third segment (femur) are yellowish-red. The femur on the hind leg is irregularly thickened and is widest near the base. The fourth segment (tibia) is white on the basal half, reddish-brown on the outer (distal) half. The last part of the leg (tarsus), corresponding to a foot, has five segments. On the front and middle legs they are reddish at the base and black at the end. On the hind legs they are all black.

The forward (anterior) half of each wing is dark, the remaining is clear. The cell at the leading edge (costal cell) is usually the same dark color as adjacent cells, but is sometimes lighter or even clear. The discal cell is entirely dark and strongly indented at the first (anterior) cross-vein, which is is located well beyond the middle of the cell.




Total Length: 7 16 to ½


Similar Species


Two-spotted bumble bee, brown-belted bumble bee, and common eastern bumble bee




June and July




Adults are active during the day and are usually found on flowers.


Life Cycle


The female grasps a bumble bee in flight and forces an egg between the bee’s abdominal segments.


Larva Food


Two-spotted bumble bee, brown-belted bumble bee, and common eastern bumble bee


Adult Food




Distribution Map



24, 29, 30.







Diptera (flies)  


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


Muscomorpha (=Cyclorrhapha)  
  Zoosection Schizophora (schizophora flies)  
  Zoosubsection Acalyptratae (acalyptrate flies)  




Conopidae (thick-headed flies)  









Conops fulvipennis

Conops lugubris

Conops nigricornis

Conops tibialis


Common Names


common eastern physocephala









On plants: The central axis of a pinna, to which pinnules are attached. On insects: The vein on the leading edge of the forewing.



On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.



The upper part of an insect’s face, roughly corresponding to the forehead.



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



The back of the head. In Odonata, Megaloptera, and Neuroptera, the upper part of the head behind the eyes.



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



The protruding, tubular mouthpart of a sucking insect.



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.



The fourth segment of an insect leg, after the femur and before the tarsus (foot).



The upper surface of an insect’s head.






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Alfredo Colon

    common eastern physocephala   common eastern physocephala  
    common eastern physocephala   common eastern physocephala  
    common eastern physocephala   common eastern physocephala  
    common eastern physocephala   common eastern physocephala  








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Other Videos
  A Parasitoid Fly that is a Wasp Mimic (Physocephala tibialis)
Nature in Motion

Published on Jul 1, 2017

As a parasitoid, this species of Thick-Headed Fly (no common name) deposits its eggs into Bumblebees. It catches the Bumblebee mid-flight, sometimes falling to the ground, the fly inserts a single egg between its abdominal segments. The larva will slowly eat it alive, beginning with the non-essential tissues first. The larva forces the Bumblebee to dig itself into the ground so it can overwinter as a pupa (this is called Adaptive Manipulation). Adults feed on nectar, as shown in this video of a male. Filmed on Common Milkweed in the Missouri Ozarks, USA, June 27, 2017. Some clips are in slow motion, none have been sped up. Here are two articles, if you would like to know more: and

Flies (Diptera) » "Acalyptratae" » Sciomyzoidea » Thick-headed Flies (Conopidae) » Conopinae » Physocephala » Physocephala tibialis

Music: Feels Good 2 B by Audionautix is licensed under a Creative Commons Attribution license (





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  Alfredo Colon

Location: Woodbury, Minnesota

common eastern physocephala  
  Alfredo Colon

Location: Woodbury, Minnesota

common eastern physocephala  
  Alfredo Colon

Location: Woodbury, Minnesota

common eastern physocephala  






Created: 12/16/2018

Last Updated:

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