Dafydd Hewitt and Lou Reed scored following Alessandro Zanni effort as the Blues looked on course to become the first Welsh region to win in Treviso this season.
But the Italians flexed their muscle at the set-piece and Alberto Di Bernardo booted the hosts out of reach as indiscipline cost the Blues.
Phil Davies’ men made a bright start in difficult conditions and Ceri Sweeney quickly booted them in front.
But their lead did not last long as Treviso rumbled forward with a driving lineout and Zanni pivoted out of Chris Czekaj’s tackle.
Treviso continued to dominate affairs but the blues survived and their regained their lead with Lloyd Williams sniping through a lineout and feeding Hewitt.
But Di Bernardo kept the scoreboard ticking and gave the hosts a 13-10 lead at the interval.
Davies rung the changes at the break with Scott Andrews, Marc Breeze and Reed all brought on to add steel to the pack.
And Reed quickly made an impact, capitalising on loose ball to drive over from close range.
Sweeney added the extras but the Blues were dealt a blow when Michael Paterson to the sin-bin and Treviso earned a penalty try at the scrum.
Di Bernardo converted and he added a pair of late penalties as the Blues left Italy empty handed.
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