arrowhead laphria

Arrowhead laphria is a small to medium-sized, bee-mimic robber fly. It occurs in the United States from the northeast to the Midwest, south to Virginia and Missouri, and in adjacent Canadian provinces. It is uncommon in Minnesota.

Adults are dark, slender, and ½″ to 11 ⁄16″ (13 to 18 mm) long.

There are two large compound eyes and three small simple eyes (ocelli). The compound eyes extend above the level of the top of the head (vertex), making the head appear hollowed out between the eyes when viewed from the front. The ocelli are arranged in a triangle on a prominent rounded projection (tubercle) in the middle of the head between the compound eyes. There is a dense mustache of long, stiff, black bristles (mystax) on the face immediately above the mouth. The antennae have 3 segments. The third segment is elongated.

The thorax is black with a narrow triangle of pale to reddish-gold hairs on the upper (dorsal) surface. The triangle is widest at the rear, about as wide as the triangular plate between the thorax and abdomen (scutellum). It narrows rapidly to at least the middle of the thorax, and fades at the tip. The hairs are iridescent and the color varies with the angle of the light. The rest of the thorax is covered with longer whitish hairs and shorter black hairs. The scutellum is covered with paler hairs and has a white bristles on the margin. The small, knob-like structures on each side of the thorax (halteres) are yellow.

The abdomen is long, slender, and black, and has six segments. The first two segments are black with white hairs on the side. Segments 3 through 6 are densely covered with orangish-gold hairs. On the male, at the rear margin of segment six, there are two black, well-defined projections. The genital bulb at the tip of the abdomen is black and very large.

The wings are clear. They are dark smoky brown at the tip, becoming paler at the base. The first and second branches of the radial sector vein (R₁ and R₂₊₃) join before the end of R₁ creating a closed cell that does not reach the margin.

The legs are stout and black. They are covered with long gray and black hairs. The last part of the leg (tarsus), corresponding to the foot, has five segments. The last segment has 2 pads.

Total length: ½″ to 11 ⁄16″

Southern arrowhead laphria (Laphria ithypyga) is very similar in appearance. On the male, the genital bulb is “substantially smaller”. At the tip of the abdomen there is just a single small projection. Neither of these characteristics is visible on most photos. The female “appears to be more robust”, and the golden triangle on her thorax “more conspicuous” (BugGuide.net). Based on the recorded sightings, this species is much less common. It has not been recorded in Minnesota, though CCESR does have it on their state insect checklist as Choerades ithypygus.

Woodland edges and openings

June through mid-August

Sources

24, 27, 29, 30, 82.

Infraorder
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.

Robber Fly (Asilidae: Laphria index) Male, Close-up
Carl Barrentine

Laphria index ORANGE ROBBER FLY
Rob Curtis

Robber Fly (Asilidae: Laphria index/ithypyga complex) Female Feeding
Carl Barrentine

Location: Woodbury, Minnesota

An Awesome Robberfly