The holotype fossil of Plecia canadensis was collected by Lawrence Lambe from outcrops of the Allenby Formation along the Tulameen River on 6 August 1906, and then subsequently described by Anton Handlirsch in 1910.

Insects from the Tertiary lake deposits of the southern interior of British Columbia, along with a series of 19 other bibionid species.

[1] Plecia canadensis has been recovered from up to four locations in the Okanagan highlands, with the type locality being on the Tulameen River "opposite Vermilion Cliff" in the Allenby Formation near Princeton, British Columbia.

[1] The Okanagan Highland sites represent upland lake systems that were surrounded by a warm temperate ecosystem with nearby volcanism.

[3] The highlands likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable.

The CLAMP results after multiple linear regressions for Princeton's gave a 5.1 °C (41.2 °F), and the LMA returned a mean annual temperature of 5.1 ± 2.2 °C (41.2 ± 4.0 °F).