Our big birch has finally given up after decades of bronze birch borer and sapsucker damage. Rows of regular horizontal holes about one-quarter-inch in diameter cover the trunk from bottom to top. These are caused by sapsucker woodpeckers drilling for sap in the tree. Initally, borer damage reduced the flow of water and food within the tree, causing limbs to die each year. The sapsucker feeding finally finished the tree off.
Unfortunately, sapsucker damage is a common cause of tree damage and is easy to identify. While the rows of holes on our birch tree are horizontal, the birds might also drill vertical rows. There are many holes close together. Sapsucker damage shouldn’t be mistaken for insect damage. Insect holes are much smaller and with bronze birch borers are “D”-shaped. Besides their size, insect holes are also random on the trunk of the tree. In addition, insect holes might have boring dust (frass) in or on the ground under them whereas sapsucker holes will not.
The presence of sapsucker holes does not necessarily mean the tree is infested with insects. According to the Pacific Northwest (PNW) Pest Management Handbook, “Unlike other woodpeckers, sapsuckers are actually drilling for the tree sap, not for insects living in the tree. However, sapsucker damage may attract opportunistic damaging insects, which the sapsucker may then subsequently feed on.”
Sapsuckers feed on both deciduous and evergreen trees.
“They prefer foraging on trees with thin bark, such as birch. Older conifers with thick and ridged bark are not as susceptible to sapsucker-caused damage.”
A tree can recover from minor damage but intense feeding can weaken a tree allowing it to succumb to insects or fungi.
If a tree is attracting sapsuckers, wrap burlap or other coarse fabric around the trunk where they are feeding. Sometimes shiny objects “such as pie tins, streamers, or beach balls” can be hung in a tree as scare tactics. The PNW Handbook advises, “If the sapsucker appears to favor a specific tree, it may be best to leave that as a sacrifice tree as the bird may then leave other trees alone in favor of this preferred feeding spot.”
“Sapsuckers, like all woodpeckers, are protected by the Federal Migratory Bird Treaty Act, so a permit would be required for lethal control.”
I guess I will have to appreciate them as part of the Northern Nevada wildlife experience. My poor tree!
JoAnne Skelly is associate professor and Extension educator, Emerita at University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org.