tachinid fly

Widespread but uncommon in Minnesota

July through August (CCESR)

Xanthomelanodes arcuatus is a small to medium-sized tachinid fly. It occurs in the United States and southern Canada. It is uncommon in Minnesota. There are four species of Xanthomelanodes in North America north of Mexico. Only Xanthomelanodes arcuatus occurs in Minnesota.

Adults are¼″ to 5⁄16″ (6 to 8 mm) in length.

There are two large compound eyes at the side of the head and three small simple eyes (ocelli) in a triangle at the top of the head. The compound eyes are brown. They do not meet at the top of the head in either sex. The antennae have three segments. The second segment has a longitudinal groove (suture) on top. The third segment has a long, forward-pointing bristle (arista) on the upper side. The arista is bare, not feather-like (plumose). The upper face (frons), corresponding to the forehead, is black and relatively narrow, 0.21 times the width of the head. The area between the frons and the compound eye (frontorbital plate) may be white, yellowish-white, or yellow. On each side of the face below the antenna there is a sunken area (parafacial) defined by the inner margin of the compound eye on the outside and an inverted V-shaped groove (ptilinal suture) on the inside. The parafacial is mostly hairless, with at most a few hairs on the upper third. There are two long, stiff bristles (vibrissae) below the antenna bases. The vibrissae arise far above the lower margin of the face. There are long sensory organs (palps) attached to the mouth. The protruding mouthpart (proboscis) is not slender and piercing.

The thorax has three segments. Each segment has four principal exoskeletal plates, one above, one below, and one on each side. The upper (dorsal) plates, from front to rear, are the prescutum, scutum, and scutellum. The prescutum is mostly black with broad, yellow lateral margins and a narrow yellow rear margin. There is a distinct groove (transverse suture) across the thorax separating the prescutum and scutum. The scutum is black, sometimes with a narrow yellow rear margin. The scutellum is black and has several pairs of bristles. The bristles at the base are longer than those at the tip, and are widely divergent from each other. On the underside, the exoskeletal plate on the first segment (prosternum) is bare. The plate on the second thoracic segment (katepisternum) usually has three bristles.

The abdomen is mostly yellow with distinct black markings on the upper (dorsal) side of each segment. The last two segments are sometimes completely or almost completely black.

As with all flies, there is only one pair of wings, the hind wings being reduced to small, knob-like structures (halteres) that are used for balance in flight. The halteres are yellow. At the base of each wing there are two rounded lobes (calypters) that cover the halteres. The calypters are large, conspicuous, and yellow, yellowish-white, or white. The wings are mostly clear but with dark veins and a broad, smoky-brown band on the outer edge (costal margin). The first posterior cell (R₅) is closed before the wing tip

The third leg segment (femur) is mostly yellow, blackish-yellow at the tip. The fourth segment (tibia) is mostly blackish-yellow, black at the tip. The last part of the leg (tarsus), corresponding to the foot, is black.

True bugs (Suborder Heteroptera)

Sources: 24, 27, 29, 30, 82.

Location: Woodbury, MN