The Cubs placed Wesneski on the 15-day injured list Saturday with a right forearm strain, Andy Martinez of Marquee Sports Network reports.
Wesneski pitched 1.1 shutout innings out of the bullpen during Friday's loss to Arizona, though he appears to have come away from his latest appearance with an injury. He'll be held out of action until at least Aug. 4, and the Cubs will recall Hunter Bigge from Triple-A Iowa to fill the opening in their bullpen.