From Brattleboro to Burlington, Vermonters owning " sugar bushes " _ stands of sugar maple trees _ are drilling tap holes and waiting for the clear white sap to drip from the wounds into collecting buckets.
12.
If a maple harvester taps a tree too early in the late-winter season the tap hole will quickly dry up and heal, shutting off the flow of sap from the tree's xylem _ its equivalent of upward-flowing blood vessels.
13.
This can be either continuous removal or in batches, with the tap holes being blocked with clay at the end of a tap, and then reopened by drilling or with a thermic lance when it is time for the next tap.
14.
In an average year, a harvester drills two or three 3-inch-deep tap holes in a tree, and when there are too many holes the tree dies, just as if it had been " girdled " _ circled by a continuous cut that severs its circulatory system.
