Landscape shade tree trunk (species not confirmed from the photo) with many small, square-to-round holes drilled in loose horizontal rows through the bark.
Summary
Neat rows of small holes ringing a trunk or limb are the signature of sapsuckers, woodpeckers that drill "sap wells" and come back to feed on the sap and the insects it attracts. In Tucson they mostly visit in the cooler months. A few rows are usually cosmetic, but heavy, repeated drilling can girdle a limb, and the wounds give decay and insects a way in.
Key symptoms
- Small holes (roughly pencil-eraser size) in tidy horizontal rows, often several rows stacked.
- Holes can be fresh and weeping sap, or old and partly closed over by new bark.
- Sap staining, sometimes with dark sooty growth on the bark below.
- Usually concentrated on one favorite tree or one section of trunk.
Likely causes, ranked
- Sapsucker feeding. The regular, grid-like pattern is the giveaway; birds return to the same tree year after year.
- Other woodpeckers searching for insects. These leave larger, irregular holes, often where borers are already present.
- Insect exit holes. Borer exit holes are scattered, not in rows (see the Wood-Boring Beetle guide).
Look-alikes and how to tell them apart
- Borer exit holes: random placement, often D-shaped or oval, with galleries under the bark.
- Woodpecker excavation: larger, ragged holes or chiseled patches chasing insects.
- Lenticels: natural breathing pores in the bark; flush with the surface, not drilled.
What to check on site
- Are holes fresh (weeping, clean edges) or old and closing?
- How much of the trunk circumference is drilled; a full band is more serious.
- Signs of borers, cankers or decay around the holes.
- Overall canopy health and watering, since stressed trees are slower to close wounds.
Treatment
- Usually no treatment is needed for light, old damage; healthy trees close the holes over time.
- Protect a favored spot with loosely wrapped burlap or hardware cloth over the drilled area during the season the birds are active. Remove it afterward so it does not girdle or trap moisture.
- Do not seal or paint the holes.
- Keep the tree vigorous with deep, infrequent watering.
- Sapsuckers are protected migratory birds; do not harm them.
What to expect and how to monitor
- Expect return visits in following years; check the same tree each winter.
- Watch for dieback above heavily drilled bands, and for borer or decay activity in the wounds.
Worried about a tree? Text Justin, ISA Certified Arborist, at (520) 451-8790 or email Justin@TimberxTrees.com. TIMBERx serves Tucson, Oro Valley, Marana, Vail, Sahuarita, Green Valley and Benson.
