Tonga'uiha (left) scored his tries in the 24th and 49th minutes
Soane Tonga'uiha scored two tries as Northampton Saints continued their good start to the Premiership season with a convincing win at Wasps.
Wasps' misery was compounded with England centre Riki Flutey suffering an injury to his right leg.
Saints fly-half Stephen Myler scored the opening try, before Tonga'uiha was shoved over for a second.
Chris Ashton, Tonga'uiha and Courtney Lawes touched down to secure a bonus point, before Ben Jacobs' consolation.
While Wasps will be left analysing their five-try drubbing, Flutey's injury will be of concern to England manager Martin Johnson.
The 30-year-old Flutey could be a doubt for the autumn internationals with his native New Zealand, Australia, Samoa and South Africa after he was helped from the pitch in the first half, unable to put weight on his leg.
Northampton are up to second in the Premiership, just one point behind London Irish after the win.
Myler got the scoring under way for the Saints with a penalty after a collapsed scrum but he missed a second kickable penalty.
However, he made up for that by side-stepping his way to the line and surging over for the opener. Tonga international Tonga'uiha then added a second try, which Myler converted, before Flutey's injury.
Ashton grabbed Myler's grubber to add a third try, although there was a suspicion of offside and Myler added two more points.
Dave Walder opened the Saints' account with a penalty, although Myler cancelled that out to make it 25-3 at half-time.
Tonga'uiha secured the bonus point when he was pushed over, from a line-out catch and drive like his first score. Myler converted again to take his personal tally up to 17 points.
Lawes added their fifth try after another surge through the Wasps defence, and Jacobs' late try after charging down Ashton's chip and Walder's conversion were scant consolation for the Wycombe-based hosts.
Wasps director of rugby Tony Hanks: "Riki's pretty sore at the moment. It's an injury to the calf, quite high. He'll be assessed by England tonight when he goes into camp with them.
"Hopefully he won't be out for too long. These things can take a day or two before you learn how bad they are, but he was definitely pretty sore.
"There's a sense of embarrassment at having let the supporters and our families down. Our supporters have been great for us in the last few weeks, but that performance wasn't befitting of them.
"It's a mixture of disappointment, frustration and embarrassment. It's a horrible feeling when you come second like that."
Northampton Saints director Jim Mallinder told BBC Radio Northampton: "It's a place where we've never come and won. It's fantastic to get that result and it was an outstanding team performance.
"Our forwards dominated theirs, we put pressure on their scrum and our line-out was accurate.
"You're always searching for the perfect performance - there are still things to improve on. But we put together a plan and a performance that went through the 80 minutes."
Replacements: Kefu for van Gisbergen (66), Jacobs for Flutey (30), Berry for Simpson (58), Beech for Payne (41), Ward for Webber (60), Broster for Taulafo (41), Veale for Cannon (41), Betsen Tchoua for Rees (66).
Replacements: Ansbro for Downey (70), Geraghty for Myler (65), Powell for Dickson (62), Dreyer for Tonga'uiha (70), Sharman for Hartley (70), Mercey for Mujati (62), Sorenson for Day (60), Clark for Dowson (60).
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