It takes 40 gallons of tree sap, boiled down in an evaporator, to make one gallon of Maple syrup. My neighbors used to gather around the wood-fired evaporator in early April as the kids would gather up the sap they tapped from the trees on our property, stand around chatting while it boiled away into syrup. The adults drinking rum to keep warm, the kids waiting impatiently with plates of clean snow... then dribbling out the new syrup onto the snow (turning it into a taffee-like treat) the bottling the rest to sell to local gift shops. After taking out money for the cost of the cans and bottles, the profits were divided among all the kids who did the hard work tapping and gathering every afternoon. Each family would receive a gallon or two for their own use. Nice annual social event in rural Vermont. This goes on every night as long as the sap is running. That requires below freezing temps at night and above freezing during the day. By the end of April, it's gotten warmer and the sugaring is done for the year.