About Blera analis (Macquart, 1842)
This species is a fly, scientifically named Blera analis (Macquart, 1842). For terminology used in this description, see Morphology of Diptera. Blera analis can be recognized by its yellow face, shiny black thorax, and black abdomen that is broadly orange at the apex. Adults measure between 9 and 13 mm in length. A similar species, Blera fallax, is found in Europe.
Head: In males, the frontal triangle is bare and shining light orangish-yellow on the anterior portion, and broadly pollinose on the posterior portion. In females, the front is orangish-yellow, shining on the lower portion, and dusted with short yellowish pile on the upper portion. The upper third of the vertex is blackish. The face is light orangish-yellow, covered with a light dusting of white pile; it is distinctly projecting and shiny at the base of the antennae. There is a black spot below the lower eye margin. The antennae match the face in being orangish-yellow, with the first and second segments bearing some black pile on their upper surfaces. The flagellum is large and rounded, and the arista is reddish-black. The antennal process is gently convex across its middle. The eyes are reddish-brown: male eyes are slightly holoptic, while female eyes are slightly separated. The occiput is black, with white dusting near the eyes.
Thorax: The scutum is entirely metallic greenish-black, covered with whitish pile that is denser along the humeri (postpronotum). The pleurae have tufts of dense, short white hair dusted with white pollen.
Abdomen: The abdomen is shiny bluish-black, covered with short black pile, with an orange apex. Segments 2 and 3 are black, and have long white hair along their sides. Segment 4 is yellow-orange: males have a black V-shape at the base in the center, while females have a larger, more rounded black U-shape. Segment 5 is entirely yellow-orange, with some black pile on the anterior portion and orange pile on the rest. Black coloration encroaches to varying degrees onto segment 4, usually forming a more or less triangular expansion. The rest of the abdomen is distinctly orange-yellow, with matching orange-yellow pile.
Wing: The wings are hyaline with a yellowish tinge along the front edge. Vein R4+5 is almost straight and joins the costa just before the wing tip. The first posterior cell r4+5 is acute at its apex and extends almost to the wing margin before the wing tip.
Legs: The legs are primarily black, covered with a mix of black and light yellow pile. The femora are black, with light yellow tips. The tibiae are brownish, densely covered with white pile, and are more yellowish-orange at the base and tips; hind tibiae are more yellowish overall than the other tibiae. The front and middle tibiae are more brownish in their middle section. The tarsi are light yellow, with the last segment black. The tip of the femora, the base and end of the front and middle tibiae, and the narrow base of the legs are light yellow. The end of the hind tibiae, and all tarsi except the last two segments are light yellow.
Distribution: Blera analis is found in northeastern North America.
