--- title: Bronze Birch Borer: Dying Birch Trees in Nevada url: https://battleborntreeservice.com/tree-guide/bronze-birch-borer/ business: Battle Born Tree Service address: 6301 US Highway 50 East, Carson City, NV 89701 phone: 775.232.8243 hours: Office Monday-Friday 8:30 am-5:00 pm; phones answered seven days a week; 24-hour emergency service credentials: ISA Certified Arborist WE-11728A on staff; Nevada Business License # 20131580674; fully insured type: Tree service (removal, crane work, pruning, stump grinding, defensible space, snow removal, firewood) --- - [Home](https://battleborntreeservice.com/) - [Tree guide](https://battleborntreeservice.com/tree-guide/) - Bronze birch borer # Bronze birch borer Bronze birch borer is a beetle whose larvae tunnel under birch bark, and the first sign is usually thinning and dieback in the top of the crown. Once a birch is heavily infested its chance of survival is low, so a tree dying from the top down is usually removed. - **What it is:** Agrilus anxius, a wood-boring beetle - **Trees affected:** Birch, especially paper and European white birch - **Where in our area:** Lawn birches on valley lots and at Tahoe, about 4,000 to 6,500 feet - **Key sign:** Thinning from the top, D-shaped exit holes about 3/16 inch, bark ridges - **Stress link:** Borers prefer stressed or weakened trees This borer is the most serious insect pest of paper birch, according to the USDA Forest Service, and Utah State University reports European white birch severely affected by borers in much of Utah. This page covers what to look for, which trees, what an arborist checks and when pruning or removal is the answer. ## What does bronze birch borer damage look like? The crown thins first at the top, with small branches in the upper canopy attacked first, as Utah State University describes. Leaves in the top are small and sparse, and branches die. On the trunk and branches, look for D-shaped exit holes, about 3/16 inch across, where adults have chewed out. Utah State says the larvae's galleries can show as raised bumps or ridges on the bark. If the bark is peeled back, winding tunnels packed with sawdust spiral around the branch or trunk, University of New Hampshire Extension notes. Peeling bark off a standing tree is an arborist's job. - Dieback from the top of the crown - D-shaped exit holes - Raised ridges on bark - Small, sparse leaves ## Which trees and which elevations? Utah State lists paper birch as most susceptible, with silver and gray birch also susceptible and Monarch, Japanese white and river birch more resistant. New Hampshire Extension adds that gray, western, water and sweet birch can be attacked. The birches on our lots are the white-barked kinds on the [white birch](https://battleborntreeservice.com/tree-guide/white-birch/) page, and [quaking aspen](https://battleborntreeservice.com/tree-guide/quaking-aspen/) is a different tree that the borer is not a leading pest of. Elevation is a stress factor rather than a limit. Valley lots at Reno (4,505 feet) and Carson City (4,680 feet) get hot summers and about 7 to 9 inches of precipitation a year, which is hard on birches. Utah State suggests cooler, moister conditions may keep borers down, which is why Tahoe birches at 6,243 feet and up may be better off. ## Why does a birch get attacked? The Forest Service says the borer attacks injured, overmature or declining trees, and Utah State says borers prefer stressed or weakened trees, and drought and iron chlorosis are common stresses. A birch with a hot south exposure, dry soil or lawn-root competition is in the stressed group. See [iron chlorosis](https://battleborntreeservice.com/tree-guide/iron-chlorosis/) and [drought stress and dieback](https://battleborntreeservice.com/tree-guide/drought-stress-and-dieback/). Adults are around from late May through August, peaking in July, with usually one generation per year; the larvae under the bark do the damage. ## What does an arborist check? The arborist checks how much of the crown is dead, whether the dieback is only at the top or has reached the lower crown, whether exit holes and galleries are on the trunk and what stress factors are present. They also look at neighboring birches. - Percent of crown dead or thin - Exit holes and galleries on trunk or limbs - Soil, water and sun stress - Nearby birches - Fall zone ## When is pruning or removal the answer? University of New Hampshire Extension advises pruning and destroying dead or heavily damaged branches by early May. In practice that means a light infestation caught early, where the rest of the tree is green. Utah State puts adult beetles in flight from late May through August, which is why the New Hampshire advice is to finish pruning by early May. Removal is the answer when the dieback has reached more than the top of the crown or when exit holes show on the main trunk. New Hampshire notes that once a tree is heavily infested, its chance of survival is low. A dead birch drops limbs; see [tree removal](https://battleborntreeservice.com/tree-services/tree-removal/) and [stump grinding](https://battleborntreeservice.com/tree-services/stump-grinding/). ## What does Battle Born Tree Service do about bronze birch borer? The free estimate is where this gets decided. We assess the tree in person, and the arborist's call is one of pruning out dead wood or removal. We hold a Nevada Business License (#20131580674) and are fully insured, and two of the eight crew members are ISA Certified Arborists (WE-11728A is one person's credential). We identify the problem, prune out dead or hazardous wood and remove trees that cannot be saved; we do not spray, inject, fertilize or apply products. ### Sources - [Utah State University Extension: Bronze Birch Borer](https://extension.usu.edu/planthealth/ipm/ornamental-pest-guide/arthopods/wood-borers/bronze-birch-borer) (read October 17, 2026) - [University of New Hampshire Extension: Bronze Birch Borer Fact Sheet](https://extension.unh.edu/resource/bronze-birch-borer-fact-sheet) (read October 17, 2026) - [USDA Forest Service, Fire Effects Information System: Betula papyrifera](https://www.fs.usda.gov/database/feis/plants/tree/betpap/all.html) (read October 17, 2026) ### Talk to the office [775.232.8243](tel:775.232.8243) | Monday to Friday | 8:30 am - 5:00 pm | |---|---| | Saturday and Sunday | Office closed, phones answered | Phones answered seven days a week. 24-hour emergency service. [Free estimate](#quote) ### Keep reading - [White birch](https://battleborntreeservice.com/tree-guide/white-birch/) - [Quaking aspen](https://battleborntreeservice.com/tree-guide/quaking-aspen/) - [Iron chlorosis](https://battleborntreeservice.com/tree-guide/iron-chlorosis/) - [Drought stress and dieback](https://battleborntreeservice.com/tree-guide/drought-stress-and-dieback/) - [How to tell if a tree is dead or dying](https://battleborntreeservice.com/guides/is-my-tree-dead-or-dying/) - [Tree removal](https://battleborntreeservice.com/tree-services/tree-removal/) ### Terms on this page [Arborist](https://battleborntreeservice.com/glossary/arborist/) [The full glossary](https://battleborntreeservice.com/glossary/) ## Questions people ask Still have a question? Call [775.232.8243](tel:775.232.8243). Phones are answered seven days a week. ### Why is the top of my birch dying? Top-down dieback is the classic sign of bronze birch borer, and stress is the usual setup. An arborist can look for exit holes. ### Can I save a borer-infested birch? A birch with a few dead tips and a green lower crown may hold on. A heavily infested one rarely does. ### Does bronze birch borer attack aspen? University of New Hampshire Extension says it has been found in beech and aspen stands, but birches are the main host.