I love my large holly, but I looked at it the other day and noticed a bunch of very organized holes in one area of the trunk, maybe 50 or so. The holes are arranged in rows. What is causing this? JY

It sounds like you are describing damage to your holly by a yellow-bellied sapsucker. That name almost sounds like something from an old cartoon rather than a real critter, but yellow-bellied sapsuckers are very real and related to woodpeckers. Those holes are one of the ways the sapsuckers feed.

Sapsuckers will eat a variety of insects (including ants), fruit, and berries, but in this case they are going after the sap in the trees. Using their beaks, they drill these small 1/4-inch holes into the bark in very neatly spaced rows. In doing this they are creating little sap wells if you will. These holes reach into the bark deep enough for them to reach the phloem layer of cells in the tree. Phloem is the vascular tissue in trees that transport the sugars created by the leaves down into the roots of the tree. These little sap wells fill up with the moving of these sugars allowing the sapsucker to revisit this feeding site multiple times to eat. They will also eat insects like ants they find using their sap wells for food.

Sapsuckers are a migratory bird with the males arriving at the breeding grounds before the females. Courtship of course includes the males showing off, trying to impress the females by point their bills up to show off their brightly colored throat feathers.

Nests are typically built in the cavity of a tree such as aspen, poplar, or birch. Sapsuckers tend to return to the same tree for years in a row but rarely use the same nesting hole. Their nests can be found anywhere on the tree between six and sixty feet above the ground.

Females tend to deliver 5 or 6 eggs and both the male and female take turns incubating the eggs. Males tend to take the night shift. After almost a month, the young birds are ready to leave the nest and their parents begin teaching how to feed on the sap of trees.

There are over 250 different species of woody plants that sapsuckers enjoy dining upon including pecans, maples, pines, elms, apples and of course hollies. So, there’re not very picky. This type of damage can make the tree more vulnerable to disease.

To discourage sapsuckers on your favorite trees, you can wrap hardware cloth or burlap around the areas being damaged. The Federal Migratory Bird Treaty Act prevents the shooting of sapsuckers, and the reality is that even if you eliminated the problem birds, others would likely move in to re-populate the area.

For the most part we can just enjoy the amazing precision and engineering skills of these birds without much concern for our trees. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: James Solomon, USDA Forest Service, Bugwood.org