cobalt hover fly

not listed

NNR - Unranked

not listed

Pelecinobaccha is a recently defined genus with 53 species. Only one species occurs north of Mexico.

Cobalt hover fly is an uncommon, small, slender, hover fly. It occurs in the United States east of the Great Plains and in southern Ontario Canada. It is uncommon throughout its range, rare in Minnesota. Larvae feed on scale insects in trees and possibly also on aphids. Adults are found from mid-June to late October in forests.

Adults are ⅜″ to ½″ (8.7 to 11.5 mm) in length and mostly black with pale yellow markings. In photographs the markings often appear white.

The head is wider than the thorax. The rear part of the head is strongly concave and close to the thorax. There are two large compound eyes on the sides of the head and three small simple eyes (ocelli) in a triangle on top of the head. The compound eyes are bare, with no erect hairs. On the male they meet at the top of the head. On the female they do not. The forehead (frons) is mostly black with a narrow pale yellow stripe on each side. On the female the frons is strongly narrowed at the top. The face narrows toward the bottom. It is pale yellow except for a narrow black stripe in the middle that does not reach the lower margin. The protruding mouthpart (proboscis) is short and fleshy. The antennae are short, shorter than the head, and have just three segments. The first two segments, the scape and pedicel, are short, not longer than wide. The third segment is no more than two times as long as wide, and it has a stiff, forward-pointing bristle (arista) above.

The thorax is large, black, and shiny. The middle and largest plate (scutum) is hairless above except for one or two transverse rows of long hairs near the front margin. On each side of the scutum, in the shoulder (humeral) area just behind the head, there is a small plate (postpronotum). The postpronotum is bare, with no hairs or bristles. Unfortunately, this is not visible without first removing the fly’s head. The small rear part of the thorax (scutellum) is blackish-brown and more or less translucent.

The abdomen is slender and long, at least ten times as long as the width of the second abdominal segment (tergite). It is strongly petiolate, very narrow in front and oval behind. Tergite 1 is very short and is shiny bluish-black. Tergites 2 through 6 are mostly opaque black above with bluish-black on the margins. Tergite 2 is long and slender. Tergites 3 and 4 each have a small, triangular, pale yellow spot on both sides. Tergite 5 usually has at least a trace of these spots. On the male, tergite 5 is visible when viewed from above.

The front and middle legs are pale orange. On the hind legs the third segment (femur) is pale orange on the basal half, dark brown on the outer half. The fourth segment (tibia) is yellow on the basal third, dark brown on the outer two thirds.

The wings are dark brown on the front half, clear on the rear half. The medial discal (dm) cell is always clear. There is a false (spurious) vein between the radius (R) and media (M) veins and parallel to them. It is not a true vein but rather a streak of discoloration. The anal cell is long and is closed near the wing margin. The marginal, R₅, and M₂ cells are also closed. The R₄₊₅ vein is forked.

⅜″ to ½″(8.7 to 11.5 mm)

Forests

Late June to mid-October

Scale insects

Sources

24, 29, 30, 82.

All of the species in the genus Pelecinobaccha were formerly included in the genus Ocyptamus. A recent molecular phylogenetic study (Mengual, Ximo [2012]) showed that the genus was not composed of a common ancestor and all of its descendants (non-monophyletic). The authors divided the genus into several monophyletic subgroups but declined to split the genus. One of the groups was Pelecinobaccha. A later revision of the Pelecinobaccha (Miranda et al., 2014) raised it to the genus level.

See https://www.inaturalist.org/observations/133551832

Location: South Minneapolis, Howe neighborhood

See https://www.inaturalist.org/observations/133551832