Narrow-headed marsh fly

Conservation Status

IUCN Red List

not listed

NatureServe

not listed

Minnesota

not listed

Description

Narrow-headed marsh fly is a robust, medium-sized, ⅜″ to ⅝″ long hoverfly. It is somewhat bee-like in appearance.

The head is rounded in the front, not flattened. There is a shiny, orange, vertical stripe on the front on the face. There are two large compound eyes and three very small simple eyes (occelli). The compound eyes of the male, like the female, do not meet at the top of the head, and are narrowed abruptly at the top of the face. On the female the margin is straight. This gives the male a much narrower area between the compound eyes at the top of the head (vertex). The occelli are are arranged in a triangle on the vertex. On the female the vertex and upper part of the face (frons) are completely covered with short black hairs and are narrower than the width of the pair of tubercles that bear the antennae (antennal process). The antennae are short.

The thorax is brownish-black with four longitudinal stripes. The two middle (dorsal) stripes are white, whitish, or pale yellow.

The abdomen is brownish-black with lemon yellow horizontal stripes. The first stripe is incomplete, interrupted in the middle (dorsally). The others are usually complete but not always. The male has 3 yellow stripes. The female abdomen is longer and has 4 yellow stripes. The plate between the abdomen and thorax (scutellum) is large, convex, and more or less translucent.

The wings are relatively large. The second cell on the leading edge of each wing toward the tip (pterostigma) is relatively broad and tinted brown. It does not resemble a cross vein. The marginal cell (R1) is open.

The legs are mostly yellow with some dark brown or blackish-brown markings. The third segment of the hind leg (femur) is not spurred.

Size

Total length: ⅜″ to ⅝″

Similar Species

Broad-headed marsh fly (Helophilus latifrons) yellow abdominal stripes are broader. The male vertex is broad, not narrowed. The lower third if the female frons is covered with yellow hairs. The frons and vertex are wider than the antennal process. The legs are less extensively marked with black.

Habitat

Ecology

Season

Late March to early October

Behavior

Life Cycle

Larva Food/Hosts

Submerged plant litter in ponds, mud, manure, and silage.

Adult Food

Distribution

Sources

24, 27, 30, 82, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 9/17/2026).

Helophilus (Helophilus) fasciatus Walker, 1849 in Bánki, O., Roskov, Y., Döring, M., Ower, G., Hernández Robles, D. R., Plata Corredor, C. A., Stjernegaard Jeppesen, T., Örn, A., Pape, T., Hobern, D., Garnett, S., Little, H., DeWalt, R. E., Miller, J., Orrell, T., Aalbu, R., Abbott, J., Abreu, C., Acero P, A., et al. (2026). Catalogue of Life (2026-08-26 XR). Catalogue of Life Foundation, Amsterdam, Netherlands. https://doi.org/10.48580/dgyy9

Telford, Horace S.. (1939). The Syrphidae of Minnesota. University of Minnesota. Minnesota Agricultural Experiment Station.