Thereva egressa Coquillett, 1894

Thereva egressa Coquillett View in CoL

Specimens examined (12). BC: Fort St. John; Koksilah River; Monkman Provincial Park, Limestone Lakes; Okanagan Falls, White Lake; Robson; Vernon; Victoria; Wapiti Lake. RBCM, SEM.

Database and literature records (94). BC:Adams Lake;Anarchist Mountain;Aspen Grove; Clinton, Porcupine Creek; Cranbrook; Elko; Fife; Hedley; Kamloops; Keremeos, Twin Lakes; Keremeos Creek, 1 km N Highway 3A; Lillooet; Osoyoos; Osoyoos, Mount Baldy Road; Robson; Robson, Waldie Road; Rock Creek; Similkameen; Vernon; Vernon, Vernon Hill; Yale. CASC, CNCI, CUIC, EMEC, OSUC, SEM.

iNaturalist records (1). BC: Okanagan Falls, White Lake (iNat 55185825).

Conservation status. BC: S5

Distributional notes. There are few records of Thereva egressa on the British Columbia coast (Victoria, Koksilah River) but it is common in the southern Interior from the Similkameen drainage (Aspen Grove, Keremeos Creek) east through the Okanagan (Osoyoos) and Boundary region (Fife, Rock Creek) to the Rocky Mountains (Elko). It is recorded north to the Thompson Valley (Adams Lake, Kamloops) and the Peace River region (Wapiti Lake).

Ecoprovinces and other designations. BC: Georgia Depression, Southern Interior, Southern Interior Mountains, Central Interior, Sub-boreal Interior, Boreal Plains.

Range. Cordilleran. Southern British Columbia and Alberta south to California, Arizona, and Colorado ( Webb et al. 2013).

Biological notes. Flight period: 12 May–31 July. Thereva egressa has been collected in the alpine zone in northeastern British Columbia and in regenerating Tsuga heterophylla / Thuja plicata forest on Vancouver Island. Forest and steppe habitats are typical ( Holston & Irwin 2005).