Gardening in Gwinnett: Sapsuckers feed on maples, other trees, but seldom cause harm

Often the extension office receives calls from homeowners concerned about the appearance of small holes in rows in the bark of their maple trees. The holes sometimes form rings around the trees. What is the source of these holes? Will the holes harm the trees?

The holes are the result of the yellow bellied sapsucker bird, a close relative of woodpeckers. They are migratory birds and are most prevalent in our area during the spring and fall months. Maples are among their favorite trees, but also they like to feed on pecans, Bradford pears and several other trees. Research has shown the birds feed on more than 250 species of trees and vines. The sap they feed on composes up to 20 percent of their diet and is especially important during the fall or any time when other food supplies are in short supply. The birds also feed on insects they find in and on the bark. They peck a small hole in the trunk of the tree and suck up the sap flowing out of the hole. The holes are roughly 1/8 inch in diameter, and they are evenly spaced up and down and around the trunk, appearing as if drilled by a machine. Often the sap will flow down the trunk of the tree causing a black "sooty mold" to grow, which may be unsightly but will not harm the tree. The feeding activity of sapsuckers differs from insect borers, which can harm the trees. Holes caused by borers are not as many in number and are not evenly spaced around the tree.

Many homeowners who observe the sapsucker activity on their trees become concerned. However, sapsuckers seldom cause harm to the trees; in fact, trees can have hundreds of holes in their bark and not suffer at all. There are circumstances in which a particular tree may become a favorite feeding site for the birds creating a large number of holes in the bark. If the tree has been weakened due to other factors, such as drought or previous insect or disease problems, the sapsucker activity can increase the damage. The wounds themselves can be a source of attraction for other insect pests and diseases.

Inspect the trees to determine the level of damage and the type of control measures desired. The sapsuckers are not easily deterred, so take the necessary control measures as soon as possible. What can be done? Wrap the area of the trunk being attacked by the sapsuckers with a burlap or hardware cloth. Another control method is scaring the birds away by placing an artificial predator, such as an owl or snake on or around the tree. Also, hanging reflective objects in the trees, such as aluminum foil or shiny pinwheels, will discourage the birds since they dislike shiny or flashy objects. Leave these devices in place for a few weeks after you have noticed the activity has ceased to make sure the birds do not come back. One important thing to remember is that these birds are federally protected birds and killing them is illegal.

They are one of nature's more interesting curiosities and are best left alone in most cases since they seldom cause any appreciable damage to the trees they on which feed. For more information on sapsuckers and to ask any questions you may have about them if they are observed in your yard, please contact the Gwinnett County Extension office.

Timothy Daly is an agricultural and natural resource agent with the Gwinnett County Extension Service. He can be reached at 678-377-4010 or timothy.daly