The Super League leaders hammered their near neighbours for the third time this season, a task made considerably easier by playing against 12 men for 75 minutes.
Ashley Klein's early dismissal of Michael McIlorum destroyed any prospect of a contest, while another Wigan player, Richard Mathers, could be in trouble for a high tackle on Lee Gilmour.
Even with a full compliment and perfect discipline, however, Wigan would have made little impression on a St Helens side with half an eye on next weekend's cup semi-final against Leeds.
"It's tough enough playing that team with 13 men," said the Wigan coach, Brian Noble, of McIlorum's sending off. "He's pretty devastated. He feels responsible."
Wigan had a late setback when their full-back and goal kicker, Pat Richards, was taken ill. Saints were a lot closer to full strength, including Leon Pryce, named at stand-off despite an assault charge hanging over him.
It started ominously for Wigan with McIlorum losing the ball in a tackle and Sean Long celebrating his 300th appearance for Saints by sending Gilmour over.
A bad start got immeasurably worse when McIlorum was sent off after five minutes for a high tackle on Adie Gardner.
Keiron Cunningham forced his way over from dummy half in familiar fashion after 10 minutes and Long landed his second goal with Saints already threatening to run riot.
However, Gareth Hock stood up in a tackle and got his pass away to Thomas Leuluai to put Wigan on the scoreboard, and Cameron Phelps added the goal.
After a penalty against Hock for dissent had put Wigan on the back foot, James Roby scrambled over for Saints' third try.
Immediately before half-time, Wigan's habit of losing the ball near their own line caught up with them again to allow Gardner to score.
Wigan started the second half in the same vein when the ball bounced off Stuart Fielden for Jon Wilkin to touch down. Chris Flannery's kick ricocheted to give Gidley an even simpler score.
Long then grabbed a try, but Wigan's situation would have looked better if they had not had two tries disallowed by the video referee. They got one by Mickey Higham, but only after Gardner had his second for Saints.
Wigan: Mathers, Colbon, Goulding, Carmont, Phelps, Barrett, Leuluai, Fielden, McIlorum, Coley, Hansen, Tomkins, Hock. Substitutes: Higham. Paleaaesina, O'Carroll, Mossop.
St Helens: Wellens, Gardner, Gidley, Talau, Meli, Pryce, Long, Graham, Cunningham, Hargreaves, Gilmour, Wilkin, Sculthorpe. Substitutes: Roby, Cayless, Flannery, Fa'asavalu.
Referee: A Klein (Keighley).
l Huddersfield have appointed Nathan Brown as their new coach. The Australian, who is in charge at St George-Illawarra, will arrive at the end of the NRL season on a three-year deal.