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What are these holes on my willow tree? #861504

Asked March 14, 2024, 6:57 PM EDT

What are these holes on my willow tree?

Baltimore County Maryland

Expert Response

That looks like the work of one of our native woodpeckers, the Yellow-bellied Sapsucker, which spends the winter in our area.
They create two types of holes in tree bark to get sap to flow out. They either feed on the sap itself, any insects attracted to it, or both. One hole type looks like this -- fairly rounded and in horizontal rows. The other is more of a rectangular patch, shallower and in more of a vertical or gridded arrangement, almost like lace when the bark is riddled with this "sap well" type. As a protected bird, people cannot directly interfere with their activities, though frankly there isn't a reliable way to discourage them from "tapping" a tree anyway. You can learn more about the birds on the linked pages (one includes an image gallery where you can view the sap well types).

Sapsucker trunk damage rarely causes serious health problems for a tree, though when it does, nothing can be done except to cut back any canopy dieback. (This is more likely on a smaller shrub with extensive damage, such as for hollies and viburnums, rather than on trees.) As noted in N.C. State's page about this bird, you might be able to wrap the trunk of a vulnerable species in burlap (taking care not to make it too taut), but keep in mind that such an attempt might accidentally let actual insect pests harbor underneath, or trap moisture against the bark. Plus, even if a successful deterrent is used, the birds will simply pick other trees in the area, possibly spreading one damage event into several.
No action is needed for the sapsucker holes; don't coat them or treat them with anything. Trees that don't suffer any ill consequences of sapsucker drilling will gradually seal-off and scar-over those holes over time. Fortunately, we've seen examples of much older Magnolia and Cedar trees with years of extensive cumulative sapsucker drilling and no discernable impacts on their health or longevity.

Christine



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