The presence of holes in the bark of trees is a common problem found during the examination of landscape and woodland trees. If the holes appear in uniform rows or columns (or both) the cause is something smarter than insects. A bird would be the likely suspect.
Yellowbellied sapsuckers are larger than starlings but smaller than robins (about 8 inches long). They have black-and-white backs and off-white breasts. The yellow belly is evident on only some birds (and in just the right lighting condition). Males have red on the throat and top of the head. Females have little or no red coloration.
These woodpeckers live during the summer in the northern United States and southern Canada, migrating south through Iowa between mid-September and mid-October. They overwinter in the southern United States, migrating back north between late March and mid-May. These are the only times that trees are damaged in Iowa.
Where the birds spend the summer or winter, they can feed heavily enough on trees to kill them. In Iowa, the damage is noticeable but does not significantly weaken the trees. Rows of holes about 1/4 inch in diameter on tree trunks are caused by the yellowbellied sapsucker woodpecker. These birds attack many species of trees but prefer pines, birches, maples, and apple.
Yellowbellied sapsuckers are unlike most woodpeckers. Sapsuckers feed primarily on sap rather than insects. Sapsuckers drill a series of horizontal or vertical rows of holes in tree trunks and eat the sap that runs out. Holes are typically located between the branches.
Protecting a large number of trees is usually not practical. However, applying tree wrap or screening to the trunks of attacked trees during the time that the birds are migrating through the state might be useful for individual trees. Do not keep the wraps on the trees year-round because increased disease problems can result. There are no insecticides or sprays to control woodpeckers.
The birds are protected by state and federal laws, as well as by an international wildlife pact, so it is unlawful to attack the birds directly.