Yellow-bellied Sapsuckers, Vol. 10, No. 05
Sphyrapicus varius
Order: Piciformes
Family: Picidae
“Something keeps boring holes in our maple and magnolia trees. Could this be some kind of beetle?”
It is birds, not beetles, that cause these holes. Yellow-bellied sapsuckers are small, migratory woodpeckers with unique feeding habits. They peck holes in trees like other woodpeckers, but they are mining for sap instead of insects. The holes they make are known as sap wells, to which they periodically return to lap up accumulated sap with their brush-tipped tongues. Other woodpeckers have long, barb-tipped tongues to extract wood borers from their galleries. Sapsuckers do eat insects, as well as small fruits and berries, and the inner bark of trees, but tree sap constitutes a significant portion of their diet, especially in winter and spring.
One of the distinguishing characteristics of sapsucker holes is that they occur as evenly spaced holes arranged in rows, usually running horizontally across the trunk. Often there will be several parallel rows of holes, and favored trees will bear scars of sap wells from previous years. Sometimes the rows are oriented vertically, but this is less common. When the birds return to feed on the sap, they tend the holes to encourage continued sap flow. An individual sap well may resemble an emergence hole of a wood boring beetle, in that it is round and about the diameter of a pencil, but lines of evenly spaced holes are a sure sign of sapsucker feeding. Sapsuckers sometimes make shallow square or rectangular holes, which are less likely to be mistaken for insect damage.
Although they feed on hundreds of types of trees, maples and other trees with relatively thin bark and sugary sap are preferred, and favorite trees are visited annually in spring and fall by migrating sapsuckers. Sapsuckers don’t breed here in the South; they fly up to Canada or the northern-most states of the Eastern US to nest. But they come south for the winter, with many going into Mexico and Central America. Populations in our area are highest in spring and fall as additional migrants pass through, heading to or from areas farther south. I may see an occasional sapsucker in the maples at my house in January, but they are most common in February and March.
Most trees are surprisingly tolerant of repeated sapsucker feeding, suffering little long-term adverse effects to growth and vigor, but excess sap flowing down the trunk can cause trunks to be black and unsightly with sooty mold, and unusually heavy, repeated feeding can adversely affect tree vigor and even cause mortality.
Control: Because sapsuckers are migratory songbirds, lethal methods of control are not allowed without a special permit. One of the most practical means of control is to loosely wrap trunks of sapsucker-favored trees with bird netting or burlap during the heavy migration period. Be sure to limit the time such wraps are in place, install them strategically, and remove promptly after the birds pass through, or your control efforts may end up causing more damage than the sapsuckers. Keeping trees that are regularly damaged by sapsuckers properly watered and fertilized will help speed recovery and maintain tree vigor.
See Audubon Bird Guide Yellow-bellied Sapsucker for more information, including a map of their migration pattern. Also see MSU Extension Publication 3302, Recognizing Sapsucker Damage in Yard Trees.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
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