tiger crane fly

Nephrotoma alterna is a small tiger crane fly. It occurs in the United States from Maine to northern Florida, west to South Dakota and Colorado. It also occurs in southern Canada from Nova Scotia to Manitoba.

Adults are seen from early May through late August, but there is a clear peak in late June to early July. They are active at night (nocturnal) and at dusk and dawn (crepuscular). They are found at the edges of deciduous forests and in moist to wet areas near lakes, ponds, rivers, and streams.

The female body length is 11⁄16″ to ¾″ (18 to 20 mm). The male is much smaller, with a body length of 7⁄16″ to 9⁄16″ (11 to 14 mm).

The head is mostly pale yellow to yellow. The top of the head (vertex) is brownish yellow, the area between the eyes is brown, and a broad mark on the back of the head (occiput) is dark brown to black. The snout (rostrum) is short and has a beak-like point. The upper (dorsal) part of the rostrum is brown to dark brown. The lower jaws (maxillae) have sensory structures (palpi) attached. The last segment of each palp is antenna-like and very long, much longer than the subapical segment. There are two large, black, compound eyes and no simple eyes (ocelli). The antennae have 13 segments. The first segment (scape) is yellow, and on the male, it is tinted with brownish black above. The second segment (pedicel) is short and light brown to dark brown. The remaining segments are dark brown to black.

The thorax is yellow with dark markings. The markings are usually dark brown to black, but they may be much lighter. The main exoskeletal plates on the upper side are, from front to back, the pronotum, scutum 1 (also called , scutum 2, and the scutellum. The pronotum is small and collar-like. It is yellow above and dark on the sides. Scutum 1 is the largest plate. It has three broad, dark, longitudinal stripes. The lateral stripes are distinctly curved downward at the front. A distinct, V-shaped groove (transverse suture) on top near the wing bases separates scutum 1 and scutum 2. There is a black spot at each end of the transverse suture. The front side corners of scutum 2 are dark. The scutellum is small and dark.

The abdomen is long, slender, and pale yellow to brownish yellow, with variable brown to black (dark) markings. On the male, the first abdominal segment (tergite 1) is usually dark above, light on the sides. Tergites 2 through 5 or 6 have dark, forward pointing, more or less triangular markings on the rear three-fourths to four-fifths. Tergite 7 may be entirely dark or dark only at the rear. Tergite 8 is entirely dark. On the female, the markings on tergites 2 through 7 are usually much smaller, on only one third to one fourth of each tergite.

The legs are stilt-like, very long, very slender, and very fragile, easily separated from the body. On each leg, the third segment (femur) is light brown, dark just at the tip; the fourth segment (tibia) is light brown to brown, dark just at the tip; and the last part of the leg (tarsus) is dark brown.

The wings are very long, very narrow, and mostly clear. On each wing, the tip is tinged with black, and the pterostigma is dark brown. There is a distinct dark seam across each wing along the basal part of the R₄₊₅ vein and the r-m cross vein. The seam is less distinct along the m-cu vein, M4 vein, and the end of the CU vein. Each wing has two anal veins that meet the inner margin.

Female body length: 11⁄16″ to ¾″ (18 to 20 mm)

Male body length: 7⁄16″ to 9⁄16″ (11 to 14 mm)

Edges of deciduous forests; moist to wet areas near lakes, ponds, rivers, and streams

Early May through late August

Sources

24, 27, 29, 30, 82, 83.

Oosterbroek P. (1984) A revision of the crane-fly genus Nephrotoma Meigen, 1803, in North America (Diptera, Tipulidae). Part II. The non-dorsalis species-groups. Beaufortia 34: 117‒180.

Attempts to segregate the subfamily Tipulinae into tribes has been unsuccessful due to the near constant addition of new species and genera.

Mating Of Large Crane Flies(🆔Nephrotoma Alterna)
🫧WORLD & NATURE🫧

Alfredo Colon
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