Craig Attwell bagged a try for the visitors with Joseph Evans adding a conversion and four penalties. However, home advantage and four tries with a bonus point, saw the Scarlets home on a night of outstanding rugby.
Josh Smart and Scott Williams bagged tries in the first half for the Scarlets and further five pointers from Edward Siggery and Stefan Phillips saw them home. James Stephenson added two conversions for good measure.
Down the road at Landarcy, the Ospreys put their season back on track after losing out to the Blues North last time out.
Deeke Morse, Chad Punchard and Guy Jones crossed for first half tries as the Ospreys eased into the interval 15-6 to the good and after the break there were further tries from scrum half Ryan Jones and replacement prop Luke Myatt. Replacement outside half Craig Davies added a penalty to make sure whilst for thye South, Lauren Quick helped himself to three penalties and a conversion with captain and flanker Joe Poole scoring his side's only try.
An injury to Ross Wardle meant the game was held up for 20 minutes in the first half, but thankfully Wardle has suffered nothing more than ligament damage to his neck.
Ospreys High Performance Manager Dai Arthur said: "It was another good game, but above all we are just pleased to learn that Ross Wardle is not too badly injured."