What Animals Eat Tree Bark? (5 Surprising Wood-Boring Pests)

Introduction: Understanding Bark Consumption and Wood-Boring Pests

Wood is a remarkable material. Its durability, versatility, and natural beauty make it essential in construction, woodworking, and, of course, firewood. As someone deeply involved in wood processing and firewood preparation for over two decades, I’ve learned firsthand the importance of understanding how various factors can compromise wood’s integrity. One crucial aspect is the threat posed by animals and pests that consume tree bark and bore into the wood itself.

“What Animals Eat Tree Bark? (5 Surprising Wood-Boring Pests)” is a question that strikes at the heart of sustainable forestry and responsible wood management. Ignoring the impact of these creatures can lead to significant losses, whether you’re a homeowner protecting ornamental trees, a small-scale logger managing a woodlot, or a firewood enthusiast ensuring a quality supply. This article isn’t just about identifying the culprits; it’s about providing actionable knowledge to safeguard your timber resources. I’ll draw upon my experiences, from felling trees in the Pacific Northwest to curing firewood in the harsh winters of the Midwest, to offer practical solutions and preventative measures.

Key Terms and Concepts

Before diving into the specifics, let’s define some essential terms:

• Bark: The outermost layer of a tree, providing protection from the elements and pests. It’s composed of the outer bark (dead tissue) and the inner bark (phloem), which transports nutrients.
• Phloem: The living tissue beneath the outer bark, responsible for transporting sugars produced during photosynthesis from the leaves to other parts of the tree. This is a favorite food source for many bark-eating animals.
• Xylem: The wood itself, composed of dead cells that transport water and minerals from the roots to the leaves. Xylem provides structural support to the tree.
• Cambium: A thin layer of actively dividing cells between the phloem and xylem, responsible for growth in diameter.
• Green Wood: Freshly cut wood with a high moisture content.
• Seasoned Wood: Wood that has been dried to reduce its moisture content, making it more suitable for burning or construction.
• Wood-Boring Pests: Insects or animals that tunnel into wood, causing structural damage and potentially introducing decay.

Animals That Eat Tree Bark

While many animals might nibble on bark occasionally, some species rely on it as a significant food source. Understanding their habits and preferences is key to protecting your trees.

1. Beavers: Nature’s Loggers

Beavers are perhaps the most well-known bark eaters. These industrious rodents are not just nibblers; they are significant ecosystem engineers.

• Dietary Preferences: Beavers primarily consume the inner bark (phloem) of trees, which is rich in nutrients. They favor softwoods like aspen, willow, cottonwood, and birch.
• Impact: Beavers fell trees for food and building materials (dams and lodges). This can lead to deforestation in localized areas and alter water flow patterns.
• Identification: Look for trees with conical or hourglass-shaped chew marks around the base. You might also find dams and lodges in nearby waterways.
• Personal Experience: I once helped a local landowner mitigate beaver damage to his apple orchard. We installed wire mesh cages around the base of the trees to prevent beavers from accessing the bark. This simple solution proved highly effective.
• Mitigation:
  • Tree Guards: Wrap the base of trees with wire mesh or plastic guards.
  • Beaver Deceivers: Specialized structures that prevent beavers from damming culverts.
  • Population Control: In some areas, trapping or relocation may be necessary.

2. Deer and Elk: Browsing Giants

Deer and elk are opportunistic browsers that can cause significant damage to young trees, especially in winter when other food sources are scarce.

• Dietary Preferences: Deer and elk will strip bark from young trees, particularly conifers like pine, fir, and spruce. They also eat buds and twigs.
• Impact: Bark stripping can girdle trees, cutting off the flow of nutrients and water, leading to death. This is especially damaging to young seedlings in reforestation projects.
• Identification: Look for ragged bark stripping, often several feet above the ground. You might also find deer or elk tracks and droppings nearby.
• Personal Experience: I’ve seen entire stands of newly planted Douglas fir decimated by deer browsing. The economic impact on the forestry industry can be substantial.
• Mitigation:
  • Fencing: Enclose vulnerable areas with deer-proof fencing.
  • Tree Shelters: Individual plastic tubes that protect seedlings from browsing.
  • Repellents: Apply commercially available deer repellents to trees. These often contain ingredients like putrescent egg solids or capsaicin.
  • Habitat Management: Encourage the growth of alternative food sources for deer and elk.

3. Rabbits and Hares: Low-Lying Nibblers

Rabbits and hares are small but persistent bark eaters, particularly during winter when their food options are limited.

• Dietary Preferences: Rabbits and hares will gnaw on the bark of various trees and shrubs, including fruit trees, ornamentals, and young conifers.
• Impact: Girdling can occur, especially on young trees. This can kill the tree or stunt its growth.
• Identification: Look for smooth, clean-cut gnawing marks near the base of trees. Snow cover can allow rabbits to reach higher parts of the trunk.
• Personal Experience: I lost several young apple trees in my orchard to rabbit damage one winter. I now protect them with wire mesh cages.
• Mitigation:
  • Wire Mesh Cages: Encircle the base of trees with wire mesh cages, burying the bottom edge to prevent rabbits from digging underneath.
  • Tree Guards: Plastic or cardboard tree guards can also provide protection.
  • Repellents: Apply commercially available rabbit repellents.
  • Habitat Management: Reduce rabbit habitat near vulnerable trees by removing brush piles and tall grass.

4. Voles and Mice: Hidden Dangers

Voles and mice are small rodents that can cause significant damage to trees, often going unnoticed until the damage is severe.

• Dietary Preferences: Voles and mice feed on the bark of trees, especially near the base, often under the cover of snow or leaf litter. They prefer young trees with thin bark.
• Impact: Girdling can occur, especially on young trees. Their damage is often hidden beneath the snow, making it difficult to detect early.
• Identification: Look for irregular gnawing marks near the base of trees, often hidden by vegetation or snow. You might also find vole runways in the grass.
• Personal Experience: I once discovered extensive vole damage to a row of young blueberry bushes. The damage was hidden beneath a thick layer of mulch.
• Mitigation:
  • Vegetation Control: Keep the area around trees clear of grass, weeds, and leaf litter to reduce vole habitat.
  • Wire Mesh Guards: Bury wire mesh guards around the base of trees to prevent voles from accessing the bark.
  • Trapping: Use mousetraps or vole traps to reduce populations.
  • Predator Encouragement: Encourage natural predators like owls and hawks by providing nesting sites.

5. Porcupines: Prickly Bark Eaters

Porcupines are less common than other bark eaters, but they can cause significant damage, especially in forested areas.

• Dietary Preferences: Porcupines feed on the inner bark of trees, particularly conifers like pine, hemlock, and spruce. They often climb high into trees to reach the bark.
• Impact: Porcupines can girdle branches and trunks, leading to dieback or death. Their damage is often high up in the tree, making it difficult to detect.
• Identification: Look for irregular gnawing marks on branches and trunks, often high up in the tree. You might also find porcupine droppings (small, cylindrical pellets) near the base of the tree.
• Personal Experience: I’ve seen entire stands of pine trees stripped of their bark by porcupines. The damage can be extensive and long-lasting.
• Mitigation:
  • Tree Guards: Wrap the base of trees with sheet metal or wire mesh to prevent porcupines from climbing.
  • Trapping: Trapping may be necessary in areas with high porcupine populations.
  • Habitat Management: Remove or thin out dense stands of conifers to reduce porcupine habitat.

Wood-Boring Pests: The Silent Destroyers

While bark eaters primarily consume the outer layers of the tree, wood-boring pests tunnel into the wood itself, causing structural damage and potentially introducing decay.

Common Wood-Boring Pests

• Bark Beetles: These small beetles bore into the bark of trees, creating tunnels that disrupt the flow of nutrients and water. Severe infestations can kill entire trees. Examples include the Mountain Pine Beetle and the Spruce Beetle.
  • Identification: Look for small holes in the bark, often accompanied by sawdust-like frass. The bark may also be discolored or peeling.
  • Mitigation: Maintaining tree health is crucial. Remove dead or dying trees to prevent beetle populations from building up. Insecticides can be used in some cases.
• Woodboring Beetles (Longhorned Beetles, Metallic Wood-Boring Beetles): These beetles lay their eggs in cracks in the bark. The larvae then tunnel into the wood, creating galleries that weaken the structure.
  • Identification: Look for oval or round exit holes in the wood. You may also find larvae or their frass inside the tunnels.
  • Mitigation: Use treated lumber for construction. Inspect wood regularly for signs of infestation. Insecticides can be used to treat infested wood.
• Carpenter Ants: These ants don’t eat wood, but they excavate tunnels in it to create nests. This can weaken wooden structures and lead to collapse.
  • Identification: Look for piles of sawdust-like frass near wooden structures. You may also see carpenter ants foraging for food.
  • Mitigation: Eliminate sources of moisture that attract carpenter ants. Seal cracks and crevices in wooden structures. Use insecticides to control ant populations.
• Termites: These social insects feed on cellulose, the main component of wood. They can cause extensive damage to wooden structures, often going unnoticed until the damage is severe.
  • Identification: Look for mud tubes running along walls or foundations. You may also find swarming termites or damaged wood.
  • Mitigation: Use treated lumber for construction. Maintain proper drainage around foundations. Schedule regular termite inspections. Use termiticides to control termite populations.
• Carpenter Bees: These bees bore into wood to create nests. They prefer softwoods like cedar, redwood, and pine.
  • Identification: Look for round, smooth holes in wooden structures. You may also see carpenter bees flying around.
  • Mitigation: Fill in existing holes with wood putty or caulk. Paint or stain wooden surfaces to deter carpenter bees. Use insecticides to control bee populations.

Protecting Your Trees and Wood: A Step-by-Step Guide

Now that we’ve identified the major bark eaters and wood-boring pests, let’s discuss practical steps to protect your trees and wood.

Step 1: Prevention is Key

• Maintain Tree Health: Healthy trees are more resistant to pests and diseases. Ensure your trees have adequate water, nutrients, and sunlight.
• Proper Pruning: Prune trees regularly to remove dead or diseased branches. This improves air circulation and reduces the risk of infestation.
• Avoid Wounding: Protect trees from physical damage, such as lawnmower strikes or construction activities. Wounds provide entry points for pests and diseases.
• Choose Resistant Species: When planting new trees, select species that are known to be resistant to common pests and diseases in your area.

Step 2: Monitoring and Early Detection

• Regular Inspections: Inspect your trees and wooden structures regularly for signs of bark eating or wood-boring pests. Look for chew marks, holes, sawdust, and other signs of damage.
• Identify the Pest: Correctly identifying the pest is crucial for effective control. Consult with a local arborist or extension agent if you’re unsure.
• Document Your Findings: Keep a record of your observations, including the date, location, and type of damage. This will help you track the progress of the infestation and evaluate the effectiveness of your control measures.

Step 3: Control Measures

• Physical Barriers: Use tree guards, wire mesh cages, or fencing to protect trees from bark-eating animals.
• Repellents: Apply commercially available repellents to deter bark-eating animals.
• Trapping: Use traps to reduce populations of rodents and other pests.
• Insecticides: Use insecticides to control wood-boring insects. Be sure to follow the manufacturer’s instructions carefully and choose products that are safe for the environment.
• Biological Control: Introduce natural predators or parasites to control pest populations.
• Sanitation: Remove dead or dying trees and branches to eliminate breeding sites for pests.
• Professional Assistance: Consult with a qualified arborist or pest control professional for severe infestations.

Step 4: Protecting Firewood

Firewood can be a breeding ground for wood-boring insects. Here’s how to protect your firewood:

• Seasoning: Properly season your firewood to reduce its moisture content. This makes it less attractive to pests.
  • Process: Stack the wood loosely in a sunny, well-ventilated area. Allow it to dry for at least six months, preferably longer.
  • Measurements: Aim for a moisture content of 20% or less. Use a moisture meter to check the moisture content of the wood.
  • Timing: The drying time will vary depending on the type of wood, the climate, and the stacking method.
  • Benefits: Seasoned wood burns more efficiently, produces less smoke, and is less likely to attract pests.
• Storage: Store firewood off the ground and away from buildings. This prevents pests from spreading to your home.
  • Method: Use a firewood rack or pallets to elevate the wood. Cover the top of the stack with a tarp to protect it from rain and snow.
  • Strategic Advantages: Storing firewood properly prevents moisture buildup and reduces the risk of pest infestation.
• Debarking: Remove the bark from firewood to reduce the risk of insect infestation.
  • Tools: Use a drawknife or a debarking spud to remove the bark.
  • Techniques: Hold the tool at a slight angle and pull it along the length of the log, removing the bark in strips.
  • Benefits: Debarking firewood reduces the risk of insect infestation and speeds up the drying process.
• Burning Practices: Burn firewood completely to kill any remaining pests.
  • Method: Start fires with kindling and gradually add larger pieces of wood. Ensure that the fire is hot enough to burn the wood completely.
  • Safety Considerations: Never leave a fire unattended. Keep a fire extinguisher or a source of water nearby.

Case Studies: Real-World Examples

Let’s examine a couple of case studies to illustrate how these principles apply in practice.

Case Study 1: Protecting an Apple Orchard from Beaver Damage

A local apple grower was experiencing significant losses due to beaver activity. The beavers were felling apple trees and using them to build dams in a nearby stream.

• Problem: Beaver damage to apple trees.
• Solution: The grower installed wire mesh cages around the base of the trees to prevent beavers from accessing the bark. He also worked with the local wildlife agency to relocate the beavers to a more suitable location.
• Results: The wire mesh cages effectively protected the apple trees from beaver damage. The relocation of the beavers reduced the overall population in the area.
• Key Takeaway: Physical barriers and population control can be effective strategies for mitigating beaver damage.

Case Study 2: Controlling a Bark Beetle Infestation in a Pine Forest

A landowner noticed that many of his pine trees were dying due to a bark beetle infestation.

• Problem: Bark beetle infestation in a pine forest.
• Solution: The landowner removed all dead and dying trees to eliminate breeding sites for the beetles. He also thinned out the remaining trees to improve air circulation and reduce stress. He consulted with a forestry expert to determine the best course of action.
• Results: The removal of dead trees and the thinning of the forest helped to control the bark beetle infestation. The remaining trees were healthier and more resistant to attack.
• Key Takeaway: Sanitation and forest management practices can be effective strategies for controlling bark beetle infestations.

Tools and Equipment

• Chainsaws: Essential for felling trees and cutting firewood.
  • Specifications: Choose a chainsaw with the appropriate bar length and engine size for the size of the trees you’ll be cutting. Consider features like anti-vibration systems and chain brakes for safety. (e.g., Stihl MS 271 Farm Boss or Husqvarna 455 Rancher).
  • Felling Techniques: Use proper felling techniques to ensure that the tree falls in the desired direction and avoids damaging other trees or property.
  • Safety Considerations: Wear appropriate safety gear, including a helmet, eye protection, hearing protection, gloves, and chaps.
• Axes: Useful for splitting firewood and felling small trees.
  • Specifications: Choose an axe with the appropriate weight and handle length for your strength and experience level. Consider a splitting axe with a wedge-shaped head for splitting firewood. (e.g., Fiskars X27 Splitting Axe).
  • Splitting Techniques: Use proper splitting techniques to avoid injury. Position the wood securely on a chopping block and swing the axe with controlled force.
  • Safety Considerations: Wear appropriate safety gear, including eye protection and gloves.
• Log Splitters: Hydraulic or electric log splitters can make splitting firewood much easier and faster.
  • Specifications: Choose a log splitter with the appropriate tonnage for the size and type of wood you’ll be splitting. Consider a hydraulic splitter for larger logs. (e.g., Champion 25-Ton Gas Log Splitter).
  • Benefits: Hydraulic splitters increase efficiency and reduce the risk of injury.
• Drawknives and Debarking Spuds: Used for removing bark from logs and firewood.
  • Specifications: Choose a drawknife with a comfortable handle and a sharp blade. A debarking spud is a specialized tool for removing bark from large logs.
• Moisture Meters: Used to measure the moisture content of wood.
  • Specifications: Choose a moisture meter that is accurate and easy to use. Look for a meter that can measure the moisture content of different types of wood.
• Safety Gear: Essential for protecting yourself from injury.
  • Includes: Helmets, eye protection, hearing protection, gloves, chaps, and steel-toed boots.

Financial Considerations

• Cost of Tools and Equipment: The cost of tools and equipment can vary widely depending on the quality and features. Budget accordingly.
• Cost of Materials: The cost of materials, such as tree guards, fencing, and repellents, can also add up.
• Value of Timber: Consider the value of the timber you’re protecting. The cost of prevention and control measures may be justified if you’re protecting valuable trees.
• Potential Losses: Factor in the potential losses due to bark eating and wood-boring pests. This can include reduced timber yields, structural damage, and the cost of repairs.

Safety Standards

• OSHA Standards: Follow all applicable OSHA standards for logging and wood processing.
• ANSI Standards: Adhere to ANSI standards for chainsaw safety and other equipment.
• Local Regulations: Comply with all local regulations regarding tree removal and pest control.
• Training: Obtain proper training in the safe use of chainsaws and other equipment.
• Personal Protective Equipment: Always wear appropriate personal protective equipment.

Strategic Insights

• Sustainable Forestry Practices: Implement sustainable forestry practices to promote tree health and reduce the risk of pest infestations.
• Integrated Pest Management: Use an integrated pest management approach that combines multiple control methods to minimize the use of pesticides.
• Community Involvement: Work with your neighbors and local organizations to address pest problems on a community-wide scale.
• Education: Educate yourself and others about the importance of protecting trees and wood from bark eating and wood-boring pests.

Conclusion: Taking Action

Understanding the threats posed by bark eaters and wood-boring pests is crucial for anyone involved in wood processing, logging, or firewood preparation. By implementing the preventative measures and control strategies outlined in this article, you can protect your trees, your wood, and your investments.

The key is to remain vigilant, monitor your trees and wooden structures regularly, and take action promptly when you detect signs of infestation. Don’t hesitate to consult with professionals for assistance if you’re unsure how to proceed.

Now, take the knowledge you’ve gained and put it into practice. Inspect your trees, protect your firewood, and help spread awareness about the importance of responsible wood management. Your efforts will contribute to the health and sustainability of our forests for generations to come. The next step is yours.

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