BLACK FLIES (DIPTERA, SIMULIIDAE) AS POSSIBLE VECTORS OF LEGWORK (ONCHOCERCA CERVIPEDIS) IN MOOSE OF CENTRAL ALBERTA

A filarioid nematode of moose (Alces alces) known as “legworm” ant its possible vector, the black fly (Simuliidae), were studied in Swan Hills, Alberta from 1975 to 1977. Legworms recovered from the subcutaneous connective tissue of moose were identified as Onchocerca cervipedis Wehr and Dikans, 1935. Sixty-four percent of the moose examined were infected with adult legworm. Most adult worms (80%) were in the forelimbs. There was a linear increase in number of adult legworms with increasing age of moose. Onchocerca cervipedis microfilariae were present in the skin of the fore and hind limbs of moose during June and July only. Fifteen species of black fly were collected from live-trapped and a tame, penned moose. Individuals of Simulium decorum, S. venustum, S. vittatum, S. arcticum, S. aureum, and Prosimulium formosum took blood meals. Microfilariae of O. cervipedis were found only in blood meals of S. decorum and S. venustum, incriminating these species as possible vectors of moose legworm