For more information see:
Step 1: How Much Sap Do I Need?
Sap needs to be collected in the spring when the daytime temperatures are above freezing but below 40F. and the nights are frosty.
To make 1 gallon of syrup will take about 40 gallons of sap, depending on sugar content. So if the sap contains 2% sugar you need 43 gallons of sap to produce one gallon of syrup. Sap from a Sugar Maple is typically 2.5% concentration, so you would need about 34 gallons of sap.
Shown are leafs from the sugar maple and red maple