The Homeowners Column

The Homeowners Column

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Holes in trees – wood borer or woodpecker?

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Sandra Mason
State Master Gardener Coordinator

Got holes in your tree? A myriad of insects, often beetles or clearwing moths, have a larval form that chew wood. Some feed deeply within the tree while others such as Emerald ash borer feed just below the bark. Once larvae become adults, they chew out of the tree. We usually see the exit holes and not the critter that caused it. Once we know the species of tree we can generally narrow the possibilities to the usual suspects. Although borer insects may attack a number of species, they are branded with names such as lilac borer, bronze birch borer, dogwood borer, flatheaded apple borer, locust borer, peach tree borer, viburnum borer, and Zimmerman pine moth.

A major precursor to borer attack is a tree under stress. Stresses can come in the form of too little or too much water, compacted soils, covered trunk flare due to planting too deep, poor tree selection for site and other site or environmentally related issues. Unfortunately multiple stresses can occur at the same time. Proper tree planting and maintenance is critical to reduce borer attack. Check with your local UI Extension office or the UI Plant Clinic for help with diagnosis.

If however the holes in your tree occur in straight lines, either horizontal or vertical, than the damage is probably from Yellow-bellied sapsuckers. They are migratory woodpeckers traveling long distances, as far as Panama for the winter and into the northern parts of Canada in the summer. This woodpecker attacks Illinois trees during both spring and fall migrations. They can damage trees as they migrate through in March, April and May and again in the fall in September and October. Sapsuckers breed in the far north and rarely hang around our area in summer.

Yellow-bellied sapsuckers are medium sized woodpeckers about the size of a starling with a jumbled mix of white and black feathers. Sapsuckers are the only woodpeckers to have a bold vertical white stripe along the wing. Male sapsuckers have a red crown and throat. Sapsuckers can be found migrating through residential areas, parks and cemeteries in spring and fall.

As their name implies sapsuckers feed on tree sap. They peck shallow, one-quarter inch diameter holes. They feed on the sap as it runs out of the holes. Sapsuckers have brush-like tongues that capture the sap of trees by capillary action. They also feed on insects that are attracted to the sap, but much of their diet consists of tree sap.

Pines, spruces, birch, sweet gums and fruit trees are most commonly attacked and individual trees can be attacked year after year. Rarely does the woodpecker kill a tree in this area, but extensive feeding can weaken the tree.

Large amounts of sap may run out of the holes made in pine trees, congealing and turning white on the trunk. Although this looks alarming, it appears to have little or no effect on tree health. Because there is no apparent effect on tree health in Illinois and migratory birds need all the help they can get, a viable option is to do nothing.

If you want to protect favored trees while the birds are flying through, wrap individual trees with tree wrap, burlap, hardware cloth or other protective material during migration to prevent further damage. Remove the wrap when the migration time has passed.

Remember woodpeckers are classified as migratory nongame birds and are protected by the Federal Migratory Bird Treaty Act. This federal law and its associated international treaty make it unlawful to kill or otherwise harm woodpeckers and most other birds. Plus it would be a very uncool thing to do.

Great resource for all things bird Cornell Lab of Ornithology

Information on wildlife and how to live peaceably with furred and feathered creatures of the world

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