soldier fly

Stratiomys norma is a common, large, easily recognized soldier fly. It occurs in the Great Lakes states from New York to Minnesota, south to Pennsylvania and Nebraska, and in Ontario.

Adults are black with yellow marking and ½″ (12 to 13 mm) long.

The head is more or less hemispherical. There are two large compound eyes on the side of the head and three small but prominent simple eyes (ocelli) in a triangle at the top of the head. On the male the compound eyes meet at the top of the head. On the female they are widely separated. The face is rounded and covered with yellow hairs. On the female, the head is mostly black with a large yellow spot in the middle of the face, yellow around the compound eyes, and yellow at the top of the head (vertex). A small area surrounding the ocelli is black. On the male the head and face are entirely black. The antennae are black, long (for a fly), and are inserted just above the middle of the face. They have three segments. The first segment is three or four times as long as the second. The third segment is as long as the first two segments together, and is divided into five ring-like segments (annulated). It does not have a bristle-like appendage (arista).

The thorax is black, more or less square, and densely covered with yellowish and brownish woolly hairs. The exoskeletal plate between the wing bases (scutellum) is prominent and yellow except for a black base and two red spines.

The abdomen is as long as the head and thorax together. It is egg-shaped and has five visible segments when viewed from above, thick and convex when viewed from the side. It is black, is covered with yellowish and blackish hairs, and has yellow markings. Segment 2 has a large triangle on each rear lateral margin. Segment 3 has a small elongated triangle on each forward lateral margin; a transverse stripe at each lateral rear margin that does not extend more than half way to the middle; and a small triangle in the middle at the rear margin. Segment 4 has a elongated spot on each forward lateral margin, a transverse stripe at each lateral rear margin, and a large triangle in the middle at the rear margin. The marginal spots on segments 3 and 4 do not extend to the transverse stripe on the rear margin. Segment 5 has a very narrow lateral marginal stripe, and a longitudinal stripe in the middle that is widest in the front.

The legs are moderately long. On the male, the third leg segment (femur) of each leg is red with a broad, blackish-brown band near but not at the tip. The basal half of the fourth segment (tibia) is yellow, the outer half red. The tibia have no spurs. The last part of the leg (tarsus), corresponding to the foot, has three pads. The basal half is yellow, the outer half red.

The wings are clear and tinted brownish. There are five distinct cells at the outer part of the wing. The radial vein (R) has two branches, and they are crowded in the front of the wing. The posterior branch (Rs) has three branches. The posterior branch of Rs (R₅) ends at the margin before the wing tip. The anal cell is longer than the second basal cell and is closed near the wing tip. The knob-like balancing structures (halteres) are pale green.

Total length: ½″ (12 to 13 mm)

Near streams and ponds

Larvae live in water. Adults are found on flowers.

The female lays overlapping layers of eggs on the underside of the leaves of aquatic plants.

Small aquatic organisms

Sources

24, 29, 30, 82, 83.

Common

Orthorrhapha was historically one of two infraorders of Brachycera, a suborder of Diptera. However, Brachycera did not contain all of the descendants of the last common ancestor (paraphyletic). It was split into five extant (still existing) and one extinct infraorder. Orthorrhapha is now considered obsolete and has not been used in decades, but it persists in printed literature and on some online sources. A recent revision of the order Diptera (Pope, et al., 2011) revived the name Orthorrhapha, but this has not been widely accepted.

This species has no common name. The common name for the family Stratiomyidae is soldier flies, and it is applied here for convenience.

soldier fly Stratiomys norma 01
7/6/2024

soldier fly Stratiomys norma 02
7/6/2024

Soldier Fly (Stratiomyidae: Stratiomys norma?) Close-up
Carl Barrentine

Chelsea M.
7/6/2024

Location: Aitkin, MN

Location: Woodbury, MN

Location: Woodbury, MN