Obs. Derivation unknown: cf. F. bourreler to torment. The gadfly.
1678. Phillips (App.), Burrel-fly,… the same as Gad-fly.
1713. Derham, Phys.-Theol., IV. xv. 250 (L.). The Whame or Burrel-Fly, which is vexatious to Horses in Summer, not by stinging them, but only by their bombylious Noise.
1721. Bailey, Burrel-fly, an Insect very troublesome to working Cattle. Hence in Johnson and mod. Dicts.
