Pegomya scapularis (Zetterstedt 1846)

Pegomyia pilosa Stein
Pegomyia pilosa Stein, Ent. Nachr., xxvi, p. 322, 1900. Stein, Wien. Ent. Zeitg., xxv, p. 82, 1906. Stein, Arch. f. Naturgesch., (1913), lxxix, (A), hft. 8, p. 36, 1914. Stein, Arch. f. Naturgesch., (1915), lxxxi, (A), hft. 10, p. 126, 1916. Ringdahl, Tr0mso Museums Arshefter, xlix, (1926), no. 3, p. 33, 1928. Ringdahl, K. Svensk. Vet. Kap. Akad. Skrift. Naturskyddsarenden, nr. 18, p. 21, 1931. Tiensuu, Acta Soc. Faun. Flor. Fennica, lviii, no. 4, p. 29, 1935. Seguy, Gen. Insect., fasc. 205, p. 61, 1937.
Pegomyia flavipes Malloch (not Fallen), Rept. Canad. Arct. Exped., 1913-18, in, pt. C, p. 74C, 1919. Seguy, Gen. Insect., fasc. 205, p. 55, 1937.
Pegomyia {Pegomyia) pilosa Ringdahl, Ent. Tidskr., lix, hft. 3-4, p. 208, 1938.
The specimens of pilosa before me exhibit a marked degree of variation in color in both sexes. The male specimens from Nova Scotia have a paler aspect, in which the palpi, second antennal segments and humeral callosities are entirely yellowish; the male from Bar Harbor, Maine, is darker and has the second antennal segment rufous and the palpi fuscous at apex; the males from Mount Rainier and Alaska have the antennae nearly entirely black, in the former case the palpi are considerably infuscated. All male specimens have the characteristic development of the chaetotaxy on hind femora and hind tibiae, although in specimens from Bar Harbor and Mount Monadnock this peculiarity is not so sharply exhibited as in Nova Scotian and Alaskan specimens. In addition all femora are broadly infuscated on dorsum towards the apical region and hairs and bristles on ventral region of occiput are golden tinged, less so in the darker forms and more highly so in paler specimens. It is not improbable that males of this species which have the hind femoral bristles and hind tibial setulae more normally developed may be mistaken for those of the related form Pegomyia tenera obscurior Collin. 36 Such specimens of pilosa may
36 Collin, J. E. The Oxford University Expedition to Greenland, 1928. Diptera (Orthorrhapha Brachycera and Cyclorrhapha) from Greenland. Ann. Mag. Nat. Hist., ser. 10, VII pp. 84-85, 1931. be recognized more surely by the abnormally long bristles in the posterior series of fore femur.
The female specimen from Machias has the mesonotum considerably darkened except on scutellum and humeral callosities, and the frontal vitta is blackened on caudal half, whereas in the remaining female specimens the thorax is largely yellowish, being slightly grayish tinged on dorsum, and the frontal vitta is entirely reddish. The palpi in the Machias specimen are nearly entirely reddish, whereas in the remaining specimens they are rather decidedly infuscated apicad. The ovipositor is compressed, strongly chitinized, and seems fitted for piercing. The marginal bristles of fifth abdominal sternum are robustly developed.
The female of pilosa is difficult to distinguish from those of rufipes and tenera, all having the palpi infuscated at apex and the presutural series of acrostical bristles not widely separated from one another. In cases where female specimens of pilosa have yellow palpi, the species approaches the characters defining the female of flavipalpis. From the female of these three species that of pilosa may usually be distinguished by having the proximal half of anteroventral surface of hind femur bare, three bristles on anterodorsal surface of hind tibia and no cruciate bristles.
I have reexamined the specimens from Alaska which have been recorded by Malloch 37 as flavipes, and am of the opinion that they belong to the species pilosa, resembling in every important respect the specimens from Nova Scotia. Thus flavipes (Fallen) so far as I know has yet to be correctly recorded as occurring in North America.
Alaska: i d Bering Sea, July 1913; 1 d Nome, August 21 1916, (F. Johansen), Maine: i 6% Salisbury Cove, July 24 1925; 1 d Seal Harbor, July 29 1930, (A. L. Melander), [A. L. M.]. 1 9 , Machias, July 1922. 1 d Bar Harbor, June 15 i?2i.
New Hampshire: i 9, Mount Monadnock, July 26 1926, (A. L. Melander), Nova Scotia: i d Truro, July 13 1913, (R. Matheson); 2 d Kentville, July 13 1924, (R. P. Gorham), [C. N. C.].
37 Malloch, J. R. The Diptera collected by the Canadian Expedition, 1913-18 (excluding the Tipulidae and Culicidae). Rep. Can. Arctic Exped., 1913-18, in, Ins., pt. C, p. 74C, 1919.
Ontario: i 9 , Sand Lake, July i 1926, (F. P. Ide), [C. N. C.]. Quebec: i 9, Abbotsford, June 9 1936, (G. E. Shewell), [C. N. C.]. Washington: i d Mount Rainier, Summerland Trail, July 24 1924; 2 9, Mount Rainier, White River, July 23 1924, (A. L. Melander), [A. L. M.].