After a strong rookie season in 2010 in which he led all rookies with 20 home runs while playing all three outfield spots, Colvin is hitting just .113 with two home runs this season in 62 at-bats.
"It's something that he definitely needs to go play," Cubs general manager Jim Hendry told mlb.com. "He had a really good year for us, and since the first days of spring training, he never played up to that level.
"We're in the production business. It wasn't that he wasn't given enough at-bats. He didn't earn enough at-bats. The other guys here outplayed him, too."
Colvin, a first-round pick of the Cubs in 2006, also was a backup first baseman this season, but his troubles at the plate kept him out of the lineup.
The Cubs replaced Colvin with outfielder Tony Campana, who is batting .339 with two triples and seven steals for the Iowa Cubs. Campana, 24, has been with the Cubs organization since 2008 when he was drafted in the 13th round of the first-year player draft.