The bonus point was secure by the 35th minute and it would now take a bizarre sequence of results to deny Hawks their third crown on the trot.
Skipper Mark Sitch and Stuart Low claimed two scores each, with Mike Adamson and Gordon McFadyen completing the rout. Adamson shared the kicking honours with Murray Strang.
The consolation try for Stew-Mel was earned by prop Paul Whakakura, while Sam Hendry slotted two penalties.
At Millbrae, Ayr preserved their unbeaten home record but were made to toil all the way for their jittery 7-3 BT Premiership win by Aberdeen GSFP in a scrappy encounter.
All the scoring took place in the opening quarter, Keith Oddie edging the Dons in front with a penalty before James Noonan goaled his own try for the Seasiders.
Both teams got over the line after the interval, but could not get the ball onto the turf when it mattered.
Referee David Changleng showed yellow cards to Ayr's Paul Burke for obstruction and rival flanker Rob Currie for a professional foul.
BT Scotland Premiership Division One
Ayr (7) 7 - Aberdeen GSFP (3) 3
Currie (25) 67 - Biggar (9) 14
Glasgow Hawks (25) 61 - Stewart's Melville FP (6) 11
Hawick (12) 29 - Boroughmuir (10) 10
Heriot's 19) 24 - Stirling County (0) 10
Watsonians (17) 24 - Melrose (6) 19