The opener came on three minutes when a slack pass was pounced on by Finlay Kennedy in the middle of the pitch who took a touch and fired low past ex Lochar keeper Jake Gemmell from 20 yards.
The lead was doubled on 21 minutes when Marcus Zygadlo did well in the press and when he had closed down the defender the ball fell to Ferguson who gave Gemmell no chance.
Within 90 seconds Lochar added a third when Zygadlo side footed home at the back post.
Star’s misery continued on the half hour mark when a ball over the top from Jordan Muirhead was not controlled by the defender and Ferguson pounced to grab himself a double and make it 4-0.
Zygadlo thought he had made it five when he rounded Gemmell but a Star defender made a last ditch dash and cleared off the line.
In a rare Dalbeattie attack five minutes before the break the hosts were thrown a lifeline when Muirhead was adjudged to have handled in the box.
The spot kick was missed, however, as Ross Hunter’s attempted chip went over the bar.
The second half started with Lochar still on the ascendancy and it was not long until they stretched the lead to 5-0.
A through ball found Ferguson whose first attempt was saved by Gemmell, but the big striker knocked home the rebound for a well earned hat trick.
Dalbeattie did get a consolation when a corner went over Konar Pietsch and was knocked home at the back post by Ewan Gourlay. Thistle kept their intensity up and further increased their lead just after the hour when an excellent cross field ball from Lewis Todd released Kennedy who once again took an excellent touch and smashed home from inside box.
Lochar were in seventh heaven on 80 minutes when Robbie Hogg pounced on another slack pass in the Star defensive line to round Gemmell and knock home into an empty net.
Dalbeattie’s misery was complete on 89 minutes when a Kennedy corner was headed goalwards by Craig Adamson and there was Blair Steele lurking to volley home from five yards.
The two sides meet again in the same location next week in a Tweedie Cup semi final in what will be a completely different test.
Elsewhere, Abbey Vale were knocked out of the competition on penalties on home turf by Upper Annandale.
The sides drew 1-1 after 90 minutes, Dylan Bruce netting the Vale goal from the penalty spot, but the New Abbey side were beaten 4-1 on spot kicks.
