The latest arrests were made in recent days, bringing the total to 18.
Earlier this week, Quebec provincial police made three arrests. They are looking for seven other suspects.
So far, Richard Vallières, 34, of Loretteville and Avik Caron, 39, of Saint-Wenceslas face charges of theft, conspiracy, handling stolen goods and fraud.
CBC News has learned that Caron once worked as a financial adviser.
Between August 2011 and July 2012, thieves made off with 9,600 barrels of maple syrup from a warehouse in Saint-Louis-de-Blandford, about 95 kilometres southwest of Quebec City.
At first, $30 million worth of syrup was believed to have been stolen, but later checks established fewer barrels were missing.
Police believe the barrels were siphoned off over the course of a year.
A Quebec provincial police spokesman, Claude Denis, said more than 40 search warrants were executed in New Brunswick, Ontario and in the United States.