transverse flower fly

(Eristalis transversa)

Conservation Status
transverse flower fly
Photo by Alfredo Colon
  IUCN Red List

not listed


not listed


not listed


Transverse flower fly is a moderate-sized hoverfly. It occurs in the United States from Maine to South Dakota, south to Texas and Georgia, and in Ontario and Quebec. It is common in most of its range, including eastern Minnesota.

Adults are to 7 16 long and very hairy. Larvae of the genus Eristalis are known as rat-tailed maggots.

The head is hemispherical and slightly wider than the thorax. There are two large compound eyes on the sides of the head and and three small simple eyes (ocelli) in a triangle on top of the head. On the male the eyes meet at the top of the head. On the female they do not. The upper half of each compound eye is conspicuously covered with short erect hairs. The face is densely hairy and is not projected forward. The antennae are short and have just three segments. The first and second segments are short and mostly reddish-yellow, brownish or blackish just at the joints. The third segment is oval and mostly reddish-yellow, brownish or blackish just on the top. At the base of the third segment there is a reddish bristle (arista). The arista has sparse, fine hairs, giving it a feathery (plumose) appearance just near the base.

The thorax is large and opaque black with two grayish, broad, horizontal bands. It is covered with abundant short, erect, yellow hairs. The exoskeletal plate on the third thoracic segment (scutellum) is large, rounded, and mostly bright yellow but with a narrow black band at the base.

The abdomen is longer and broader than the thorax, elliptical when viewed from above, and convex when viewed from the side. It is black with bright yellow markings. There are five visible segments. On the male, segment 1 is very narrow and entirely black. Segment 2 has a large yellow triangle on each forward lateral margin and a bright yellow band at the rear margin. Segment 3 has a broad rectangular yellow spot on each side at the forward margin and a yellow band at the rear margin. Segment 4 has a small yellow spot on each forward lateral margin, a yellow band on the rear margin, and a grayish shining band in the middle. The abdomen is densely covered with short erect hairs, black hairs in the black areas, yellow hairs in the yellow areas. On the female the abdominal markings are very different. The triangles on segment 2 are smaller. There are no rectangular markings on segment 3. Segments 2 through 5 all have a narrow yellow band on the rear margin and a grayish shining band near the front. On segment 3 there is sometimes a narrow yellow stripe on each side at the front margin.

The legs are variable but are usually mostly black with yellow at the tip of the third segment (femur) and at the base of the fourth segment (tibia). The femur on the hind leg is slender, not thickened.

The wings are mostly clear, a little yellowish at the base. There is a spurious vein between the radius (R) and media (M) veins. The cross-vein that runs between the radius and media veins (R-M cross-vein) does so near the middle of the discal cell. The anal cell is long and is closed near the wing margin. The marginal, R5, and M2 cells are also closed.




Total Length: to 7 16


Similar Species






Late April to mid-October




Adults are found on flowers.


Life Cycle


Eggs are sometimes laid in beetles


Larva Food


Aphids and other soft-bodied insects, decaying organic matter


Adult Food


Flower pollen and nectar and aphid honeydew


Distribution Map



24, 29, 30, 82.




Common and widespread



Diptera (gnats, mosquitoes, true flies)  


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


  No Rank Eremoneura  
  No Rank Cyclorrhapha  
  No Rank Aschiza  




Syrphidae (hover flies)  




  Subtribe Eristalina  


  Subgenus Eoseristalis  



Eristalis fascicollis

Eristalis philadelphicus

Eristalis pumilus

Eristalis transversus

Eristalis vittata

Eristalis zonatus

Eristalomyia calomera


Common Names


transverse flower fly










A large bristle on the upper side of the third segment of the antenna of a fly.



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



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



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).






Visitor Photos

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Alfredo Colon
  transverse flower fly   transverse flower fly
  transverse flower fly    Photos



  Transverse Flower Fly (Eristalis transversa)
Bill Keim
  Transverse Flower Fly (Eristalis transversa)  
  Transverse Flower Fly (Eristalis transversa)
Andree Reno Sanborn
  Transverse Flower Fly (Eristalis transversa)  



Visitor Videos

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Other Videos
  Transverse Flower Fly (Eristalis transversa) - Working
Nature's Wild Things

Published on May 11, 2017

Transverse Flower Fly (Eristalis transversa) Working

Video 30 sec long - Clip 1 72% speed - Clip 2 22% speed - Audio none

Cabarrus County, North Carolina, United States

Photo Walk - 05-06-2017

  Transverse Flower Fly - August 31 2013
Don Gagnon

Published on Sep 3, 2013

Transverse Flower Fly (Eristalis transversa), Pottersville Woods, near Purington Street, Somerset, Massachusetts, Saturday afternoon, August 31, 2013, 5:02 PM - Canon PowerShot SX50 HS MVI_44538; 1:00 min.




Visitor Sightings

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Alfredo Colon

Location: Woodbury, MN

transverse flower fly

Alfredo Colon

Location: Woodbury, MN

transverse flower fly

Alfredo Colon

Location: Woodbury, Minnesota

transverse flower fly






Created: 2/18/2019

Last Updated:

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