What Animal Eats Trees? (Uncovering Bark-Boring Pests & Wildlife)

Understanding the Stakes: The Global Importance of Tree Health

Before we get our hands dirty, let’s appreciate the bigger picture. Globally, forests are under immense pressure. According to the FAO (Food and Agriculture Organization of the United Nations), approximately 10 million hectares of forest are lost annually to deforestation. While this is largely due to agriculture and urbanization, the impact of pests and wildlife cannot be ignored. Healthy forests are vital for carbon sequestration, biodiversity, and even global climate stability. Protecting individual trees, therefore, contributes to a much larger effort.

Here in North America, the Emerald Ash Borer, for instance, has decimated ash tree populations, causing billions of dollars in damage and necessitating costly removal programs. In Europe, bark beetles are wreaking havoc on spruce forests, exacerbated by climate change-induced droughts. These challenges highlight the critical need to understand what’s eating our trees and how to manage these threats effectively.

Bark-Boring Insects: The Silent Destroyers

These little guys are often the sneakiest, working their way under the bark and disrupting the tree’s vascular system. Think of it as a slow, internal strangulation.

Bark Beetles: Tiny Titans of Destruction

What they are: Bark beetles are a large group of insects, with many species targeting specific tree types. The most notorious include the Spruce Beetle, Mountain Pine Beetle, and Southern Pine Beetle.
Damage: Their damage is characterized by small entrance holes in the bark, often accompanied by “pitch tubes” – resinous excretions the tree produces in response to the attack. Under the bark, you’ll find intricate galleries carved by the beetles and their larvae. A telltale sign is reddish-brown “frass” (beetle excrement) near the base of the tree.
Where to find them: Bark beetles thrive in stressed or weakened trees. Look for them in areas with drought, disease, or previous damage. They often attack in large numbers, leading to widespread tree mortality.
My Experience: I once helped a friend clear a section of his property that had been ravaged by pine beetles. The sheer number of dead trees was shocking. We had to be incredibly careful during felling, as the weakened wood made them unpredictable. This experience reinforced the importance of preventative measures and early detection.
Control: Prevention is key. Maintain tree health through proper watering, fertilization, and pruning. Insecticides can be used, but timing is crucial – they are most effective when applied before the beetles bore into the bark. Biological control methods, like introducing natural predators, are also gaining traction.

Wood Borers: The Structural Engineers of Decay

What they are: These include Longhorned Beetles, Metallic Wood-boring Beetles (like the Emerald Ash Borer), and various weevil species.
Damage: Wood borers create larger tunnels than bark beetles, often extending deep into the wood. Their presence weakens the tree, making it susceptible to windthrow and further decay. You might see exit holes in the bark, often round or oval, depending on the species. Frass can also be present, but it’s often coarser than that of bark beetles.
Where to find them: Similar to bark beetles, wood borers often target stressed or dying trees. However, some species, like the Asian Longhorned Beetle, can attack healthy trees.
Control: Remove and destroy infested trees to prevent the spread of the borers. Insecticides can be used, but they are less effective against wood borers that have already burrowed deep into the wood. Systemic insecticides, which are absorbed by the tree, can provide some protection.

Clearwing Borers: The Master Mimics

What they are: These are moths that mimic wasps, making them difficult to spot. Common examples include the Peach Tree Borer and the Dogwood Borer.
Damage: Clearwing borers attack the lower trunk and roots of trees, creating tunnels that disrupt nutrient and water flow. Their damage is often accompanied by oozing sap and frass near the base of the tree.
Where to find them: They are most common in fruit trees and ornamental trees.
Control: Pheromone traps can be used to monitor clearwing borer populations. Insecticides can be applied to the lower trunk and exposed roots, but timing is critical – they should be applied before the larvae burrow into the tree.

Wildlife: The Larger Consumers

While insects are often the silent destroyers, wildlife can cause more visible damage, especially during the winter months when other food sources are scarce.

Deer: The Bark Strippers

Damage: Deer often strip bark from young trees, especially during the winter when other food sources are limited. They may also rub their antlers against trees, causing significant damage to the trunk.
Identifying Marks: Look for ragged edges on the bark, usually at a height that deer can reach. Antler rubbing often creates vertical scrapes on the trunk.
Control: Fencing is the most effective way to protect trees from deer. Individual tree guards, made of plastic mesh or wire, can also be used. Deer repellents, available in spray or granular form, can provide temporary protection.
Personal Anecdote: I recall planting a small orchard on my property. I didn’t protect the saplings properly, and the deer had a field day. I lost several trees before I finally installed deer fencing. Lesson learned: don’t underestimate the appetite of deer!

Rabbits and Hares: The Low-Lying Nibblers

Damage: Rabbits and hares typically gnaw on the bark of young trees near the ground. They can also clip off small branches.
Identifying Marks: Look for clean, angled cuts on the bark, typically near the base of the tree.
Control: Similar to deer, fencing and tree guards are effective. Hardware cloth, buried a few inches below the ground, can prevent rabbits from digging under the fence. Repellents can also be used.

Voles and Mice: The Underground Marauders

Damage: Voles and mice often girdle trees by gnawing on the bark near the ground, sometimes even below the soil surface. This can disrupt the flow of nutrients and water, eventually killing the tree.
Identifying Marks: Look for shallow, irregular gnaw marks near the base of the tree, often hidden by grass or leaf litter.
Control: Clear away vegetation and leaf litter around the base of trees to reduce vole habitat. Traps can be used to control vole populations. Tree guards that extend a few inches below the soil surface can also provide protection.

Squirrels: The Acrobatic Bark Eaters

Damage: Squirrels can strip bark from trees, often in search of food or nesting material. They may also gnaw on branches and twigs.
Identifying Marks: Look for irregular patches of bark missing from the trunk or branches. Squirrels often leave behind gnawed cones and nuts.
Control: Squirrels are more difficult to control than other wildlife. Tree guards can provide some protection, but squirrels are adept at climbing. Trapping and relocation may be necessary in severe cases.

Birds: The Pecking Order

Damage: Certain birds, like sapsuckers, drill small, shallow holes in the bark of trees to feed on sap. While this rarely kills the tree, it can weaken it and make it more susceptible to disease and insect infestations.
Identifying Marks: Look for rows of small, evenly spaced holes in the bark.
Control: Wrapping the affected areas with burlap or netting can deter sapsuckers. Sticky repellents can also be applied to the bark.

Other Potential Culprits: Fungi and Diseases

While this guide focuses primarily on animals and insects, it’s important to remember that fungi and diseases can also cause significant damage to trees. These can weaken trees, making them more susceptible to attack by pests and wildlife. Common examples include:

Dutch Elm Disease: A fungal disease spread by bark beetles that can kill elm trees.
Oak Wilt: Another fungal disease that can kill oak trees.
Anthracnose: A fungal disease that causes leaf spots and defoliation in various tree species.

Regularly inspect your trees for signs of disease, such as discolored leaves, unusual growths, or dieback of branches. Consult with a certified arborist for diagnosis and treatment.

Prevention is Better Than Cure: Proactive Strategies for Tree Protection

Now that we’ve identified the potential culprits, let’s talk about how to protect your trees. The best approach is a combination of preventative measures and targeted treatments.

Maintaining Tree Health: The Foundation of Defense

Healthy trees are better able to resist pests and diseases. Here are some key practices:

Proper Watering: Water trees deeply and infrequently, especially during dry periods. Avoid overwatering, which can lead to root rot.
- Data Point: Studies show that trees receiving adequate water are 30% less likely to be attacked by bark beetles.
Fertilization: Fertilize trees according to their needs, based on soil testing. Avoid over-fertilizing, which can weaken trees.
- Actionable Tip: Use slow-release fertilizers to provide a steady supply of nutrients.
Mulching: Apply a layer of mulch around the base of trees to conserve moisture, suppress weeds, and regulate soil temperature.
- Technical Requirement: Use organic mulch, such as wood chips or shredded bark, and keep it a few inches away from the trunk to prevent rot.
Pruning: Prune trees regularly to remove dead, damaged, or diseased branches. This improves air circulation and reduces the risk of pest and disease problems.
- Step-by-Step:
  1. Identify dead, damaged, or diseased branches.
  2. Use sharp, clean pruning tools.
  3. Make clean cuts just outside the branch collar (the swollen area where the branch joins the trunk).
  4. Avoid removing more than 25% of the tree’s canopy in a single year.
Soil Health: Conduct a soil test to determine pH and nutrient levels. Amend the soil as needed to provide optimal growing conditions.
- Cost Consideration: Soil tests typically cost between $20 and $50. The cost of amendments will vary depending on the type and quantity needed.

Physical Barriers: Creating a Fortress Around Your Trees

Physical barriers are an effective way to protect trees from wildlife and some insect pests.

Fencing: Install fencing around your property or individual trees to keep out deer, rabbits, and other wildlife.
- Technical Specification: Deer fences should be at least 8 feet tall. Rabbit fences should be at least 3 feet tall and buried a few inches below the ground.
Tree Guards: Wrap the trunks of young trees with plastic mesh or wire tree guards to protect them from gnawing animals.
- Actionable Tip: Choose tree guards that are tall enough to protect the tree from rabbits and voles, and wide enough to allow for trunk growth.
Netting: Cover trees with netting to protect them from birds.
- Strategic Recommendation: Use bird netting with small mesh to prevent birds from getting tangled.

Repellents: Sending the Message: “Keep Away!”

Repellents can be used to deter animals from feeding on trees.

Deer Repellents: Apply deer repellents to the foliage and bark of trees. Reapply after rain or snow.
- Real Example: I’ve had success using deer repellents containing putrescent egg solids. The smell is unpleasant to deer, but it dissipates quickly for humans.
Rabbit Repellents: Apply rabbit repellents to the lower trunk and branches of trees.
- Troubleshooting: Some repellents can damage young foliage. Test the repellent on a small area of the tree before applying it to the entire tree.
Vole Repellents: Apply vole repellents to the soil around the base of trees.
- Resource Management: Use granular vole repellents for longer-lasting protection.

Insecticides: A Targeted Approach

Insecticides should be used judiciously, as they can harm beneficial insects and other wildlife.

Contact Insecticides: Apply contact insecticides to kill insects on contact.
- Technical Requirement: Use contact insecticides with caution, as they can kill beneficial insects as well as pests.
Systemic Insecticides: Apply systemic insecticides to the soil or trunk of the tree. The tree absorbs the insecticide, providing protection from insects that feed on it.
- Specifications: Systemic insecticides can be effective against bark beetles and wood borers, but they should be used with caution, as they can also harm beneficial insects and pollinators.
Timing is Key: Apply insecticides at the appropriate time of year, based on the life cycle of the target pest.
- Case Study: A local orchard successfully controlled peach tree borers by applying insecticides in late spring, just before the moths began laying eggs.

Biological Control: Enlisting Nature’s Allies

Biological control involves using natural predators, parasites, or pathogens to control pests.

Introduce Beneficial Insects: Release beneficial insects, such as ladybugs or lacewings, to control aphids and other pests.
- Best Practice: Purchase beneficial insects from reputable suppliers.
Promote Natural Predators: Encourage natural predators, such as birds and bats, to visit your property by providing habitat and food sources.
- Idiom: “Build it and they will come.” Create a welcoming environment for beneficial wildlife, and they will help control pests.
Use Biopesticides: Apply biopesticides, such as Bacillus thuringiensis (Bt), to control caterpillars and other insect pests.
- Limitations: Biopesticides are often less effective than synthetic insecticides, but they are also less harmful to beneficial insects and other wildlife.

Sanitation: Keeping Things Clean

Sanitation involves removing and destroying infested or diseased plant material to prevent the spread of pests and diseases.

Remove Infested Trees: Remove and destroy trees that are heavily infested with bark beetles or wood borers.
- Step-by-Step:
  1. Fell the infested tree carefully.
  2. Cut the tree into manageable pieces.
  3. Burn the wood or chip it and compost it away from healthy trees.
Prune Diseased Branches: Prune and destroy branches that are infected with fungal diseases.
- Actionable Tip: Disinfect pruning tools between cuts to prevent the spread of disease.
Remove Leaf Litter: Rake up and remove leaf litter around the base of trees to reduce vole habitat and prevent the spread of fungal diseases.
- Budgeting Considerations: The cost of sanitation will vary depending on the size of the area to be cleaned and the amount of debris to be removed.

Troubleshooting: Addressing Common Challenges

Even with the best prevention strategies, problems can still arise. Here are some common challenges and how to address them:

Identifying the Specific Pest: When You’re Not Sure Who’s to Blame

If you’re not sure what’s causing damage to your trees, consult with a certified arborist or your local extension office. They can help you identify the pest or disease and recommend appropriate control measures.

Actionable Tip: Take clear photos of the damage and bring them with you when you consult with an expert.

Resistance to Repellents: When the Animals Just Don’t Care

Animals can become accustomed to repellents over time. If this happens, try switching to a different repellent or using a combination of repellents.

Strategic Recommendation: Rotate repellents regularly to prevent animals from becoming accustomed to them.

Insecticide Resistance: When the Bugs Are Too Tough

Insects can develop resistance to insecticides over time. If this happens, try switching to a different insecticide or using a combination of control methods.

Technical Specification: Use insecticides with different modes of action to prevent resistance from developing.

Environmental Factors: When Nature Throws a Curveball

Drought, extreme temperatures, and other environmental factors can stress trees and make them more susceptible to pests and diseases.

Best Practice: Monitor your trees regularly and take steps to mitigate the effects of environmental stressors, such as watering during dry periods and providing shade during extreme heat.

Case Studies: Learning from Success Stories

Let’s look at some real-world examples of successful tree protection strategies:

Case Study 1: Saving an Orchard from Deer Damage

A small orchard in upstate New York was experiencing significant deer damage, with deer stripping bark from young apple trees. The owner installed an 8-foot-tall deer fence around the perimeter of the orchard, which effectively eliminated the deer problem.

Key Takeaway: Fencing is a highly effective way to protect trees from deer.

Case Study 2: Controlling Bark Beetles in a Pine Forest

A pine forest in Colorado was experiencing a bark beetle outbreak. The forest manager implemented a combination of sanitation, thinning, and insecticide treatments to control the outbreak. They removed infested trees, thinned the forest to improve tree health, and applied insecticides to high-value trees.

Key Takeaway: A combination of control methods is often the most effective way to manage bark beetle outbreaks.

Case Study 3: Protecting Trees from Voles in a Nursery

A tree nursery in Oregon was experiencing vole damage, with voles girdling the roots of young trees. The nursery owner cleared away vegetation around the base of the trees, installed tree guards that extended a few inches below the soil surface, and used vole traps to control the vole population.

Key Takeaway: A combination of habitat modification, physical barriers, and trapping can effectively control vole populations.

The Bottom Line: Costs and Resource Management

Protecting your trees requires an investment of time and money. Here’s a breakdown of the costs and resource management considerations:

Assess Your Trees: Inspect your trees for signs of damage from pests and wildlife.
Identify the Culprits: Determine what’s causing the damage.
Develop a Plan: Create a plan for protecting your trees, based on your specific needs and budget.
Implement Your Plan: Take action to protect your trees, using the strategies outlined in this guide.
Monitor and Adjust: Monitor your trees regularly and adjust your plan as needed.

Additional Resources: Where to Learn More

Your Local Extension Office: Provides information and advice on tree care and pest management.
Certified Arborists: Offer professional tree care services.
Online Resources: Numerous websites and publications provide information on tree care and pest management.

Suppliers of Logging Tools and Drying Equipment (Examples):

Baileys: (Chainsaws, Logging Tools) – https://www.baileysonline.com/
Northern Tool + Equipment: (General Tools, Wood Splitters) – https://www.northerntool.com/
Forestry Suppliers, Inc.: (Forestry Tools & Equipment) – https://www.forestry-suppliers.com/

Remember, protecting your trees is an ongoing process. By staying vigilant and taking proactive steps, you can keep your trees healthy and thriving for years to come. Now, get out there and become the best tree detective you can be!