Treviso were fresh from humbling reigning champions Ospreys 12-6 in round one but never looked likely to come out on top in Ireland.
Munster fly-half Ian Keatley pulled the strings as well as looking infallible from the tee as he collected 14 points but his team's margin of victory deserved to be greater.
The Biancoverde seemed always to do just enough to deny the home side a second try but not always in a legal fashion and centre Alberto Sgarbi saw yellow in the second half as referee Andrew McMenemy lost patience with their methods.
Munster were forced into making a pre kick-off change after Donncha O'Callaghan was given leave to be with his wife for the birth of his second child.
O'Callaghan was replaced by Dave Foley but it was Treviso who drew first blood when Alberto Di Bernardo kicked a penalty to make it 3-0.
The lead didn't last long though. With a long line-out throw the catalyst for the try-scoring move skipper Howlett went in under the posts before the ten-minute mark.
Keatley kicked the easy conversion and he added three more points when the Italians were penalised for coming in from the side on 14 minutes.
It was 13-3 when the Treviso scrum came in for a torrid time on 24 minutes and Keatley kicked the three points again.
More Italian ill-discipline was punished on the half-hour mark with yet another penalty from the former Connacht fly-half who took the half-time margin to 13 points.
Treviso brought on the experience of Fabio Semenzato at scrum-half in place of Luca Morisi at the start of the second half but it was the home side who started the stronger with captain Howlett making a searing break from the acting fly-half position.
But his inside pass to the man with the ten on his back Keatley didn't stick and Treviso escaped from a certain try.
The Italians took the Munstermen's warning shot seriously and when two surges from centre Casey Laulala brought the home side to within five metres of the line Sgarbi was shown his yellow card for hands in the ruck.
Keatley slotted the follow-up penalty to make it 19-3 but Treviso soon cancelled it out as their forwards drove up the middle of the pitch to win a series of penalties.
Fly-half Di Bernardo took control to kick one from close range under complete silence from the Thomond Park crowd.
But they were in full voice again when club legend Peter Stringer entered the fray in place of Duncan Williams at scrum-half.
The pint-sized half-back's presence however couldn't get Munster over the line and their frustrations told in the final minutes when replacement Mike Sherry was yellow carded.
|Munster Rugby Score Card|
|Benetton Treviso Score Card|
|Alberto di Bernardo||2||6|