PORTLAND — Thieves are illegally tapping maple trees on private property in Maine and stealing sap that is used to make maple syrup.

Forest Ranger Jeff Currier says the Maine Forest Service has gotten a dozen complaints from landowners finding taps in their trees with buckets or jugs underneath to collect the sap.

Currier says he first started getting sap theft reports about five years ago, but says the number of complaints is up this year. No arrests have been made, but the culprits could face theft, malicious mischief and trespassing charges.

A typical tap produces enough sap to yield about a quarter-gallon of syrup.

The U.S. Department of Agriculture says a gallon of Maine syrup has sold for about $50 a gallon on average at retail in recent years.