London Irish (13) 42
Tries: Leguizamon, Richards 2, Hewat, D Armitage, De Vedia, S Armitage
Cons: Hewat 2
Treviso (6) 9
Pens: Goosen 3
London Irish pulled away after the break to open their Heineken Cup campaign with a seven-try victory against Italian champions Treviso.
The visitors took a shock lead through Marius Goosen's penalty but tries from Juan Manuel Leguizamon and Peter Richards put Irish 13-6 in front.
Scores from Peter Hewat and Delon Armitage gave the hosts a bonus point for scoring four tries.
And Tomas de Vedia, Steffon Armitage and Richards rounded things off.
London Irish coach Toby Booth:
"Peter (Richards) is a fantastic rugby player. What's good for him is coming back to us after being on the Premiership merry-go-round and he is mature now.
"He's a good footballer and is a little bit unconventional which provides us with a different attacking threat.
"We have set ourselves the goal of getting out of the group. You have to maximise your bonus points, win your home game and pick up what you can on the road."
London Irish: Hewat; Ojo, D Armitage, Mapusua, De Vedia; Catt, Richards, D Murphy, Paice, Lea'aetoa, Kennedy, Casey, Roche, Danaher, Leguizamon.
Replacements: Skuse, Coetzee, Hudson, Thorpe, S Armitage, Hodgson, Tagicakibau.
Treviso: Williams; Borges, Horak, Goosen, De Jager; Marcato, Picone; De Gregori, Sbaraglini, Costanzo, A. Pavanello, Van Zyl, R. Barbieri, Louw, Kingi.
Replacements: Di Santo, Vidal, E. Pavanello, Orlando, Palmer, Sgarbi, Semenzato.
Referee: Tim Hayes (WRU)