Issue: December 11
Yellow-bellied sapsuckers can make holes in the trunks of trees
Q. I think my evergreens have borers. There are numerous horizontal holes across the trunks and large branches. These holes are small and evenly spaced. Sometimes there are several rows of holes. What kind of borer is likely to do this and what can I do about them.
A. The good news is that you probably do not have borers. You probably have yellow-bellied sapsuckers. These are birds, related to woodpeckers which have strong, sharp-pointed beaks for pecking into bark and wood. Woodpeckers will often make holes in wood searching for insects under the bark, or to make their nests in hollow trees. The sapsuckers will peck through the bark to cause the trees to ooze sap on which the sapsuckers can feed. The sapsuckers will also eat insects attracted to the sap. Although you mentioned their damage to evergreen trees, they are not restricted to evergreens and may feed on many different tree species. Like their relatives, the woodpeckers, the sapsucker is a protected non-game migratory species and may not be killed (if control is necessary) without permits.
The clue that the holes you described are not due to borers is that they are in evenly spaced, horizontal groupings. A sapsucker will land on the trunk of the tree, peck a hole, take a side step and do it again. The bird repeats this over and over again forming a relatively horizontal row of nearly evenly spaced holes. The same bird may revisit the same trunk and as the holes "dry up", may then make a new row of fresh holes above or below the original row. Over time, the bird may make a rather large rectangular patch of holes in a distinctive pattern.
Now some more good news - The sapsucker rarely does enough damage to harm a healthy tree. The holes, may allow entrance to diseases (and it is possible that the birds will spread diseases), but there is often no adverse affect. The holes are not close enough to each other to girdle the tree and significantly restrict the flow of nutrients through the vasculature of the tree. Some sap is lost and consumed by the birds, but the majority goes where it is supposed to go. If a tree is not healthy, the sapsucker can do damage, however, an unhealthy tree will be a poor producer of sap and not a good candidate to feed the sapsucker. Unhealthy trees are likely to be avoided except in the case of trees that have rotted in the center and serve as excellent "hollow" trees for sapsucker nesting.
Woodpeckers may also cause similar damage, but they are seeking insects under the bark and may tear or rip the bark as they seek the insects. This damage is usually much less harmful than the damage done by the insects.
To learn more about woodpeckers and sapsuckers in New Mexico go to http://aces.nmsu.edu/pubs/_l/L-211.pdf where you can read or download NMSU Extension Publication L-211: Controlling Nuisance Woodpeckers in New Mexico.
For more gardening information, visit the NMSU Extension publications World Wide Web site at http://aces.nmsu.edu/pubs/_h.
Send your gardening questions to:
Yard and Garden, Attn: Dr. Curtis Smith
NMSU Agricultural Science Center
1036 Miller Rd. SW
Los Lunas, NM 87031
Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating.