Mike (James Delfino) and Susan (Teri Hatcher) on “Desperate Housewives.” (Ron Tom/ABC)

On Sunday, the killing off of James Denton’s character, Mike Delfino, only enabled the show to remain flat, week to week, among the 18- 49-year-old viewers who are ABC’s lifeblood. Among viewers of all ages, the episode logged 8.3 million viewers — a tick above the previous week’s 8.2 million. And a far cry from the 15 million people who tuned in to see trampy neighbor Edie Britt, played by Nicollette Sheridan, get bumped off in 2009.

Sunday also marked the nation’s shift to Daylight Saving Time, which always plays havoc on networks’ primetime ratings what with the masses saying out late that day to frisk and frolic in the extended hour of sunlight. Seriously, it’s a well-documented TV phenom.

Still, time was, the knocking off of a beloved “Desperate” regular would have attracted far more viewers.

But “Desperate Housewives” is, sadly, one of the many, many television series that has stayed at the party too long. In this, its eighth season, the show is averaging just 8.5 million viewers — a big drop from the day when it was a ratings magnet to 20 million to 30 million people. Just last season, it was still logging more than 11 million viewers.

Also not helping Sunday’s ratings: The “shocking” gunning down of Delfino had been “spoiled” a few days earlier, during testimony in the wrongful termination suit filed by Sheridan, regarding Edie’s ’09 offing.

Sheridan claims that show creator Marc Cherry killed off Edie after Sheridan officially complained that he’d “walloped” her on set. Cherry has denied the “walloping,” saying it was just a tap to the head by way of demonstrating a bit of business he wanted her to do in a scene.

Anyway, last Thursday, Denton told those jurors he was not surprised by Edie’s death because the mortality rate of characters on the show was so very high. Since the show debuted in 2004, nearly 50 people have met their maker.

Denton further said that he himself was constantly worried about his character being killed off. A short while later, on the stand, “Desperate” line producer George Perkins — asked by Sheridan’s lawyer whether his client’s character was the most high-profile one to be snuffed — responded, “You mean, until today?” And then he spoiled that Denton’s character would head to that Wisteria Lane in the sky on Sunday.

It went over big, according to press coverage of that day’s trial events.