Macquart’s deer fly

Macquart’s deer fly is a common, relatively small, deer fly. It occurs in the United States and southern Canada east of the Great Plains.

Macquart’s deer fly larvae are aquatic and predaceous, feeding on other insect larvae and on worms. Adults are active in June and July in Minnesota. They are found in open woodlands and wetlands, often near the margins of streams and ponds. Males feed on plant nectar. Females feed on the blood of mammals.

Males are relatively rare, and they are difficult to identify to the species level. Female adults are ¼″ to 5⁄16″ (6 to 8 mm) in length. The body is stout and brownish yellow with dark markings. The wings have dark markings.

The head is broad and it is covered with yellow hairs. The compound eyes are bulging, iridescent, and brightly colored. On males they meet at the top of the head. On females they do not meet. There are three simple eyes (ocelli). The dark area around the ocelli (ocellus spot) is broken up into three individual spots. Females have a large, bare, hardened area (frontal callus) on the front of the head between the compound eyes. The frontal callus is dark brown and very dull. The antennae have three segments. The first segment (scape) is light reddish yellow. The second segment (pedicel) is reddish yellow below and black above. The third segment (flagellum) is darker at the base (the plate) and the remainder (style) is black. The style is clearly ringed. The large, bare, hardened area on the face (facial callus) is mostly reddish yellow, but the raised area on each side is brown. The small, bare, hardened area on each cheek (cheek callus) is brownish yellow. The mouthparts are modified for piercing flesh. The finger-like sensory mouthparts (palps) are yellowish red and very pointed.

The upper side of the thorax is greenish yellow with a narrow brown longitudinal stripe in the middle and a broader stripe on each side. On each side of the thorax there is a brown stripe between the base of the wing and the shoulder (humeral) angle.

The abdomen is brownish yellow and it has 7 segments (tergites). The first tergite (T1) is mostly yellow. There are 2 blackish-brown, longitudinal stripes on T2 through T5. T6 and T7 are brown.

The wings are clear with dark markings, including a dark leading edge (costa), a broad dark band in the middle (crossband) and a dark spot at the tip (apical band). The area between the crossband and the apical spot (hyaline triangle) is clear. Details of the extent and shape of these markings are important identifying features of species in the genus Chrysops. The dark markings are not broken by pale areas bordering the veins. The hyaline triangle is relatively large, extending beyond cell m1. The apical spot fills more than half of cell r4 and the outer edge of cell r5. More than three-quarters of cell br is dark.

Total length: ¼″ to 5⁄16″ (6 to 8 mm)

Open woodlands, wetlands, the margins of streams and ponds

June and July

Larvae are aquatic.

Other insect larvae and on worms

Males feed on plant nectar. Females feed on the blood on mammals.

Sources

29, 30, 82, 83.

No records of Chrysops macquarti in Minnesota can be found, but the species is on the Cedar Creek Ecosystem Science Reserve Checklist of Minnesota Insects.

Common

Species
This species was formerly treated as Chrysops univittatus. An overlooked specimen in the British Natural History Museum was recently reexamined (Philip, 1961). The specimen was labeled “Baltimore” and “univittatus n.sp.” by Pierre-Justin-Marie Macquart. The specimen differs in several ways from Chrysops univittatus. Philip described it as a new species an named it Chrysops macquarti.

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

Alfredo Colon
7/7/2024

Location: Albany, NY

Alfredo Colon
6/20/2024

Location: Albany, NY