The Scarlets scored a brace in each half at New Field, Rydal School. Josh Middleton crossed the line twice in the first half while Luke Morris claimed his double in the second spell.
Blues South brushed aside the Dragons in a seven-try spectacular. Wing Joseph Williams began the tryfest in the 14th minute and started the second half with his fourth try in the 41st minute.
Man of the Match Harry Roberts touched down with team mates Ellis Eyn Benham and Matthew Morley also finding the score sheet. Callum Sheedy converted three of the seven tries and added a penalty.
The Osprey's started their season off with a home win against Blues North at Llandarcy.
Blues North's Ashley John gave his team an early lead when he crossed the line in the 24th minute but the pole position was short lived, as Ospreys Joseph Thomas answered two minutes later with a try of his own.
The Ospreys flanker Dafydd Harvey sneaked over the line just before half time to take the half time score to 17-5 in the home side's favour.
It was Blues North who added to the scoreboard first when they came out for the second half with an immediate try by front row Liam Belcher in the 41st minute but with only one successful conversion each, it was the Ospreys who took advantage of Blues North poor discipline with the lethal boot of Luke Price adding 18 points to the final score after seven successful penalties.