Tachinid fly

Cylindromyia interrupta is a small tachinid fly. It occurs in northern Europe, in Scandinavia, and across North America.

Adults are slender, wasp-like, and ¼″ to 5 ⁄16″ (6 to 8 mm) long.

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 are black, moderately long, and have three segments. The second segment has a longitudinal groove (suture) on top. The third segment has a short, forward-pointed bristle (arista) on the upper side. The arista is bare, not feather-like (plumose). The protruding mouthpart (proboscis) is slender but is not much elongated.

The thorax is narrow, barely as wide as the head. It is mostly black but appears frosty white (pruinose) in the shoulder (humeral) area. The plate between the wings (scutellum) is colored the same as the thorax. It has only one pair of long, black, bristles at the rear margin.

The abdomen is narrow, elongated, and black, and is armed with long, stiff, black bristles. The first abdominal segment is very small and is not visible from above. On the second and third segments there is a row of bristles on the upper middle and a row on each side. On the fourth and fifth segments there is a row at the rear margin. There is a white, very narrow band at the base of the second and third segments. There is also a broad reddish band that wraps around the the bottom and sides of the abdomen but is interrupted on the top, leaving a broad black stripe. It is variable in size, usually extending over most of the second segment and about half of the third.

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 wings are narrow and smoky brown. At the base of each wing there are two small, rounded lobes (calypters) that cover the halteres. The calypters are well-developed and bright white.

The legs are long, stout, and entirely black.

Total length: ¼″ to 5 ⁄16″ (6 to 8 mm)

Wingspan: ½″ (12 mm)

Open, dry, weedy areas

May to August

Stink bugs (Pentatomidae), short-horned grasshoppers (Acrididae), and moths

Nectar and pollen of flowers in the family Apiaceae (carrot).