Harrisburg beat the Fightin Phils 6-4 at FirstEnergy Stadium Saturday night, dropping the Fightins to just 3-15 in the month of May.
The Fightin Phils have now lost 18 of their last 22 overall.
David Buchanan (1-5, 5.65) took the loss on the hill for Reading.
Jim Murphy had two hits, including his ninth home run of the season.
Tommy Mendoca had a two-run triple, while Troy Hanzawa added an RBI single.
The Fightin Phils (15-25) will wrap up their series with the Senators on Sunday in Baseballtown at 1:35pm.