How to get rid of borers in fruit trees?

Lemon Tree Borer

Oemona hirta

A native pest, the larvae are known as lemon-tree borer and can cause problems to a wide range of exotic and native hardwoods, but is generally associated with citrus trees.

The adults are longhorn beetles that vary in colour from red/brown to black. The larvae tunnel into trees and cause 2 main types of damage. For most of the year they tunnel into the main stem and larger branches, but in December they dig into smaller twigs, causing these branches to die.

The tunnels formed are slightly oval and often covered in a light layer of sawdust, created by the borer as they tunnel about. Bad infestations can weaken the vigour and structure of your trees.

The adult beetles are active through spring, summer, and autumn. Where possible prune citrus trees and Kowhai in winter to avoid attracting the beetle. Prune on a dry sunny day to avoid other problems.

When harvesting fruit from citrus trees or if tidying up branches while the beetle is active make a clean cut and then seal with pruning paste.

Use the nozzle provided to spray No Borer into the small holes made by the borer. Repeat if you notice fresh ‘sawdust’.

Natural Option

For a natural option spray pyrethrum into the holes until they are drenched. The Borer can also be killed by running a guitar string or a fine wire into the holes. Repeat if you notice fresh ‘sawdust’.

Powderpost Beetles

How to Get Rid of Powderpost Beetles

The following points will help discourage powderpost beetle infestations:

  1. The first thing to do is reduce the moisture content in the wood, to less than 20% moisture. Moisture meters can be used to determine moisture level in the wood. Central heat, vapor barriers and good ventilation can help control moisture. Rough-cut lumber should be dried in a kiln to kill all stages of the beetle. Reducing moisture may not be enough to completely control powder post beetle infestations.
  2. Sanded and varnished wood will not be as attractive to adult beetles. They can not penetrate or find cracks and crevices in the wood surface in order to deposit their eggs.
  3. Don’t store valuable items in sheds and barns. Wood boring beetles are common in these areas.
  4. Infested furniture that is unfinished (unvarnished, not painted, not waxed or not sealed) can be treated with Tim-bor or Boracare. Boracare and Timbor will prevent newly hatched larvae from entering the wood. Infested furniture that can not be treated with a product like Tim-bor and Boracare can be treated in fumigation chambers. Fumigation chambers are used to fumigate infested furniture. Look for pest control operators that are licensed for fumigations.
  5. If practical, remove infested wood. If not, use residual borate insecticides such as Boracare or Timbor. Due to its long life cycle (12-18) months in the wood, you may see emerging beetles emerge even after treatment. The eggs and coming larvae will come in contact with the insecticide to kill them.
  6. The recommended borate insecticides:
    • Timbor is a powder that mixes with water. One l.5 lbs pouch is mixed with one gallon of water and sprayed to the surface area of infestation. When sprayed it penetrates the entire wood, where it will remain for several years.
    • An alternative to Timbor is: Boracare. Boracare is a liquid borate that penetrates faster initially than Timbor for the first few hours, but is equal after that. Timbor is considerably cheaper per gallon to use.
    • Note when using insecticides: Powderpost beetles life cycles vary from 3 months to a year. Emerging larvae could be maturing with adult beetles emerging for up to a year. If the wood is too dry (less than 15%), depth of penetration with the Boracare may only occur to the top 1/4 inch. To solve this, spray the wood first with water to increase moisture.
  7. Fumigation may be advisable in cases of severe powder-post beetle damage, especially where other methods have failed or where rapid elimination of the insects is critical or desired. Fumigating is advantageous where it is hard to apply borate treatments such as cramped crawlspaces. Fumigation must be done by a certified pest control operator with a fumigation license. Fumigation is non residual and will not last. Because of this, fumigation will not prevent future re-infestation if the wood is exposed to adult powder post beetles looking to lay their eggs.
    Alternatives to Fumigation describes the benefits and drawbacks to borate liquid insecticides instead of fumigation.

Inspection For Wood Boring Beetles

  • The first step to management is deciding if there is an active infestation. You may be inspecting old damage. An active infestation will have borings in piles that are accumulated on the floor below or near the holes. You may also hear a ticking sound made by the larvae. If the damage is old and not currently active, you do not have to treat.
  • Inspect periodically all exposed wood surfaces and probe them for evidence of internal damage. Evidence of attack is more common in attics, crawl spaces, unfinished basements and storage areas.
  • Again, make certain that the infestation is active(not old damage or old frass), there should be fresh frass the color of newly sawed wood, or live larvae or adults in the wood.
  • Photos courtesy of IPM Alabama

Prevention of Wood Boring Beetles

Most of the procedures which will prevent attack on wood before it is used are the responsibility of those who harvest, mill or store the wood. However those who use the wood should take precautions to reduce the chances of building an infestation into structures and furniture.

Steps to prevent beetles from infesting wood include:

  • Inspecting wood prior to purchase
  • Using properly kiln or air-dried wood.
  • Sealing wood surfaces
  • Using chemically treated wood(wood preservatives or insecticides).
  • Using good building design such as ventilation, drainage and proper clearance between wood and soil will reduce the moisture content of wood creating less favorable conditions for beetle development.
  • Central heating and cooling systems also speed up the wood drying process.

Powderpost Beetle Biology

The larvae of these beetles reduce timbers to a mass of very fine, powder-like substance. The adults do very little damage

The larvae of these beetles reduce timbers to a mass of very fine, powder-like substance. The adults do very little damage In this section, we will discuss four types of Powderpost beetles in four families: Lyctidae, Bostrichidae, Anobiidae, and Cerambycidae. Adults do little damage, and it is the larvae(woodworms)that does the major part of the damage.They go through a complete metamorphosis: adults, eggs, larvae and pupae.

You can easily recognize the work of powder post beetles. When the adults emerge, usually in June, some species leave small holes about the size of a pin in the surface of the wood; others make holes the size of pencil lead. From these holes, fine, powder like brood of larvae(woodworm) carry on their destructive feeding. Normally, these insects have a 1-year life cycle; this means that the adults will appear only once each year. And because of this habit the larvae have a feeding period of many months.

True Powderpost Beetles(Lyctidae)

Identification

The adults are tiny, less than 1/4″ in size. They are flattened and reddish-brown to black in color. Larvae (woodworm)are white, and cream colored, shaped with dark brown heads. Larvae create tunnels in the wood and become pupae. As adults, they bore out through the wood, pushing a fine powdery dust out.The shape of their holes is round,about 1/32-1/16 pinholes.

Biology, Diet and Habitations

The diet of these beetles is sugar, starch and protein found in the sapwood of hardwood. They attack woods with high moisture. Moisture content of less than 6% is ideal for keeping these beetles from attacking. In the United States, the True Powderpost Beetle is the most common. They are often found in structures that have been built from infested lumber. They can re-infest.

Areas of Attack and Damage

They attack hardwoods depositing their eggs. True Powder Powderpost Beetles breed in dead and dried hardwoods such as the dead branches and limbs of trees. Their presence is overlooked until they are discovered in stored lumber, rafters, joists, finished wood, and furniture products.

Many times the Powderpost Beetle (Lyctidae) enters lumber that is stored or cured. It later emerges afterward. Old wood antiques are frequently attacked by these beetles. Hardwoood floors such as ash, hickory, oak, walnut and cherry are frequently attacked. These hardwoods that are damaged have starch-rich sapwood and are large-pored.

True Powderpost Beetles (Lyctidae) damage is characterized by:

  • Presence of extremely fine, flour like powder falling from the surface holes. The frass left by other wood borers usually contains pellets and has a course texture and a tendency to stick together. When inspecting damage, be sure to distinguish old damage from active beetle infestations.
  • Recently formed holes and frass(sawdust like) are light in color and clear in appearance; old holes and frass are dark in color.

False Powderpost Beetle(Bostrichidae)


CREDITS: James Castner, University of Florida

Since the False Powderpost Beetles are larger than other families of powderpost beetles, their exit holes are larger. These holes do not contain frass, but the galleries contain the frass. The frass is tightly packed, tends to stick together and is meal like( contains no pellets).

The adults are 1/8-to 1-inch long, cylindrical, and reddish brown to black. The adults bore into the wood in order to lay eggs, leaving a hole larger that 1/8 inch, usually in wood less than 10 years old.

The larvae are curved and wrinkled. Their diet is dependent on the starch in the wood, they are more common in softwood ,but can attack hardwoods. They require 6-30% moisture content in the wood, and complete the average life cycle in one year.

Most of the hardwoods attacked are not those commonly found used for interior floors,woodwork or trim. Most of this species does not re infest wood after it is seasoned, so the damage is limited to that inflicted by one generation. However the speed of the damage can be considerable.

They are often found in oak, firewood and furniture.

Anobiid Powderpost Beetle (Anobiidae)- Furniture and Deathwatch Beetles

The furniture beetle is found mostly in the eastern half of the United States and it infests structural timbers as well. The Death-watch beetle is found throughout the United States. It attacks building timbers in poorly ventilated areas where moisture tends to collect. These beetles are heard at night making an audible ticking sound. It picked up the nickname,”Death watch,” from this behavior.

This insect is a common pest in crawl space timbers located in the southeastern United States. Infestations can become so severe, that loss of structural strength to sills, joists,

Various anobiid beetles attack seasoned wood in the United States. These beetles range in size from 1/32- to 3/8-inch long; however, those that attack structures are 1/8- to 1/4-inch long.

They have highly variable body forms but most are elongate and cylindrical. The first body segment (pronotum) is hood-like, hiding the head when viewed from above. The last three segments of the antenna are lengthened and expanded into a club.

The furniture beetle, Anobium punctatum, is 1/8- to 1/4-inch long, cylindrical, and red-brown to dark brown in color. It has a series of pits in rows that run lengthwise on the wing covers. The pits can be seen through the fine yellow hairs that cover the body. The last three segments of the antenna are longer than the first eight combined.

Deathwatch Beetle

The adult deathwatch beetle, Xestobium rufovillosum, is 1/4- to 3/8-inch long and is gray-brown with patches of pale hairs on the back of the body.

  • It does not have the rows of pits on the wing covers and their 11-segmented antenna end in three elongated segments that are as long as the previous five segments.
  • The larvae form tunnels in both softwoods and hardwoods. They require 13-30% moisture content.
  • Their holes are round,1/16-1/8 inches. They can digest cellulose from the wood. They are inclined to the softwoods ,for this reason they are common in crawl spaces and basements infesting the pine used as framing lumber.
  • The powder outside the holes (frass) is fine to coarse, many times with small pellets. The life cycle averages 1-3 years.
  • They commonly re-infest crawl space areas that are poorly ventilated and humidity is absorbed in the wood.


Click to Enlarge
CREDITS: Wikipedia

Furniture Beetles

Furniture beetle adults emerge in the spring from cells just below the surface of the infested wood. Soon afterward, mating occurs, and egg laying begins. The female lays 20-60 eggs in old emergence holes or cracks and v in the wood. Eggs hatch in six to 10 days. The larvae feed for about one year before pupating for two to three weeks. The wood moisture content required for larval development is 13-30%. When development is complete, the adult bores directly to the surface of the wood, emerging through a round hole 1/16- to 1/8-inch in diameter. Development under ideal conditions can be completed in one year; however, two to three years is more common. The adults are active at night. Some species are attracted to light.

These beetles commonly infest seasoned sapwood of hardwoods and softwoods. They attack structural timbers, lumber, cabinets, and furniture. These beetles re-infest, and the females usually lay eggs in the wood from which they emerged. The larvae typically follow the grain of the wood when feeding ad fill their tunnels with wood frass. The frass is a fine powder with long pellets loosely packed into the galleries.

Determine if the infestation is active before initiating treatment. Wood in structures and furniture infested by these beetles may go unnoticed until the round adult emergence holes appear in the surface. The characteristic pellets found in the frass and the consistency of the frass are useful in determining what species is infesting the wood. Infested wood can be removed and replaced with treated wood. Reducing the wood moisture content to approximately 12% slows the development of the larvae.

The surface of unpainted or otherwise unprotected wood can be treated, and the galleries injected with disodium octaborate tetrahydrate such as BoraCare or Timbor. These products kill exposed larvae and prevent re-infestation when the eggs hatch and immature larvae begin to penetrate the wood. However, the most effective way to eliminate anobiid powder post beetle infestations is to fumigate using sulfur fluoride or methyl bromide.

Long-Horned Beetles or Round-Headed Borers (Family Cerambycidae)

Most representatives of this family infest and feed on dead or dying trees. However there are many that feed on living trees. There are some of these species which begin their development in dying trees, logs, or unseasoned lumber and then complete the development as the wood seasons.

A common source for these beetles indoors is from firewood brought indoors.

A sighting of these beetles can lead to a false assumption of a structural attack. Firewood that is brought in should be used very soon after it is brought inside.

The beetles of this family lay their eggs in cracks or crevices in the bark or on the surface of rough sawn timbers. The larvae are wood borers.

Mature larvae are large, varying from 1/2 to 3-4 inches long. The body is long and narrow and a light cream color. The rear portion of the head is partly drawn into the body so that only the mandibles and other mouthparts are easily seen.

Adults vary in size from 1/2 inch to 3 inches long. They can be easily distinguished from other beetles by their long, thin antennae which may be longer than the body; hence the adults are called long-horned beetles.

The adults of these boers will emerge from the wood after it has been incorporated into the structure. They will not re infest the wood because of its dryness, but they are of great concern to property owners who find them or evidence of their activity.


Old House Borer ( from the family Cerambycidae)


Picture courtesy : UC Riverside Entomology

The Old House Borer is one of the most common from this family, with it’s larvae hollowing out galleries in seasoned softwood(pine). It is found in older buildings, but is more frequent in newer buildings,(in houses less than 10 years old).

It is well established along the Atlantic Coast, but infestations have been reported as far as Louisiana and Minnesota.

The adults are brownish-black to black, slightly flattened and about 3/4-1 inch long.

The life cycle of the old house borer ranges between three to twelve years. Because this beetle has a very long life cycle, it can make re infestations of the same piece of wood. It may be many years before serious structural damage is recognized. The exit holes of emerging adults do not occur in very large numbers until the infestation has been established for several years. This, along with the fact that larvae will do extensive feeding without breaking through the surface of the wood, make it necessary to inspect infested wood very carefully to detect old house borer damage.

Rough wood being examined should be probed or struck to detect weakness or the presence of boring dust. If exit holes are present, they will be broadly oval and about 1/4-3/8 inch in diameter.

When wood has been infested with fungi, the larval development is faster. Their powder (frass) in the tunnels are like sawdust, tightly packed.


Wood Destroying Insects

Insects that damage wood

Fortunately, only a few insects actually damage sound, dry wood. Of these, termites, both subterranean termites and drywood termites, carpenter ants and certain powderpost beetles are the primary insects that can destroy wood. Dry-rot fungi are the primary wood decay organisms where high moisture permits the fungus to grow. The potential for damage from any of these pests varies by region and climate with more damage in warm, wet climates and generally less in cool, dry climates. There are also a few that can do significant cosmetic damage but rarely impact the wood’s intrinsic strength.

The potential for insect damage in any particular geographical region also varies by insect pest. Termites, for example, tend to be of more concern in warm climates whereas carpenter ants tend to be more important in cooler climates. Damage in structural softwoods, such as posts and beams, from wood-boring powderpost beetles occurs mostly in damp/coastal climates. Powderpost beetles can damage hardwoods, like flooring and furniture, in any climate.

Shell-Guard RTU is the best way to protect your home from wood-boring beetles, termites, carpenter ants, wood rot, fungi and more. It’s active ingredient Disodium Octaborate Tetrahydrate, or borate, combines with food-grade glycol added to deepen wood penetration that can be used to both treat and prevent pests from eating wood.

Research results shows that the presence of borate in the wood does two things:

  1. It kills younger beetle larvae that are feeding in the wood.
  2. It prevents any old house borer eggs from hatching. The borate treatment interrupts the beetle’s life cycle and eventually the infestation will end.

About Wood-Boring Beetles

Wood-boring beetles invade and damage wood furniture as well as structural and decorative wood inside the building. The beetle larvae feed in and do most of the damage to wood, and when they reach the adult stage, they emerge through round exit holes, which they create by chewing through the wood surface. Adults of some species also bore exit holes through plaster, plastic, and even soft metals that might cover the underlying wood.

What are the signs that beetles are present in the wood?

  • Sawdust or frass is the first sign of beetle infestation.
  • The chewing noise made by older larvae in the wood.

The life cycle of most wood-boring beetles is similar. It starts with an adult female depositing her eggs in the wood. The eggs hatch and a small grub-like larva emerges. It’s the beetle larvae that feed on wood, and they may continue eating the wood for several months or, in some cases, up to 20 years depending on the species. There comes a time in its life cycle when it’s getting ready to make the change that the larva makes a hole to the surface of the wood, so it can get out of the wood as an adult beetle. That’s why the holes are called “emergence holes.” Typically this is the first sign that beetles are present in the wood. Once the hole is complete and the tunnel is cleared of the sawdust or frass, the larva creates a pupa case and makes the transition to an adult beetle. The adult beetle eventually emerges from the hole, feeds on pollen and nectar and looks for a mate. Once impregnated, the female beetle can start the cycle all over again.

Order Your Shell-Guard RTU or Shell-Guard Concentrate to kill any wood ingesting insect it comes in contact with.

Customer Testimonial

For active infestation I have successfully used borates against insects that are actively living in isolated spots on structures. In the pictures below, poweder-post beetles infested barn wood on my porch. I injected Shell-Guard RTU into the actual holes using a syringe made for injecting marinade into food (any plastic syringe with a tip small enough to fit the hole will work).

These holes were treated and within a day there were dead larvae. It has been more than a year and they have not returned.

How to Get Rid of Tree Borers

Having a tree on your landscape can provide shade and improve the overall look of your garden, but at the same time, it could also be at risk of damage by a group of wood-loving pests known as Tree Borers. Tree Borers is a catch-all term used to describe a number of destructive insect species who share a common characteristic of boring into tree trunks and branches and being a threat to the tree’s overall health.

Most tree borers are the larval stages of certain beetles and moths, others do damage as adults such as the bark beetle. No matter the type, tree borers need to be eliminated quickly to save your infested tree or else you may have to remove the tree entirely.

In this guide, we will show you what you can do to get rid of tree borers and what cultural practices you can use to keep tree borers from targeting your landscape tree.

Identification

Tree borers are not a specific insect type, but rather is a name to represent a group of insects that lays its eggs in the bark of a tree trunk and whose larvae eats on the wood and decays it from the inside. This rots not only the tree but also the entire landscape in some cases. Tree borers could be bark beetles, clearwing moths or flatheaded borers among others, but regardless of the species, they all bore into trees and are a hazard to its health.

To help you identify which species you have, factors like your tree species and the symptoms that you observe can help you narrow down which specific insect is doing the damage. For example, tiny holes in trunks may be the result of bark beetles; larger holes with sawdust-like residue is a clear sign of clearwing moth larvae; wet spots and dark stains in the shape of the letter D or number 0 may be the work of flatheaded or roundheaded borers.

Inspection

Where To Look

Focus your inspection on the trees on your property. Pay particularly close attention to tree trunks and tree branches. In some cases, the damage may be so severe that the tree cannot be salvaged and you may have to remove the tree.

What To Look For

As mentioned in the identification section, you should be looking for signs of tree damage. Look for holes in the trunks and branches, remnants of sawdust-like frass, dead tree limbs and cracked bark. You should also observe and note conditions of the tree and landscape and whether there has been a lot of stresses that have impacted the tree (drought, compacted soil, injuries etc.) and made it favorable for tree borers to take over as they rarely infest healthy trees.

Treatment

If you have confirmed that tree borers are infesting your tree and wish to try and salvage your tree, you will need to conduct a treatment using professional products. We recommend first using a contact insecticide such as Sylo Insecticide to the tree trunk, limbs, and bark to kill any active borers are inside the tree. This is a pyrethroid that delivers a quick knockdown of insects on trees.

Once the active borers have been killed off, we recommend applying Dominion 2L via soil treatment around the tree for continued protection against tree borer damage and reducing the likelihood of future infestations. Dominion 2L is a systemic insecticide which means the product is absorbed in through the roots and to the entire tree to control tree borers.

Step 1: Sylo Insecticide Treatment

Sylo Insecticide is a synthetic pyrethroid insecticide that contains the active ingredient Cypermethrin and serves as a good contact insecticide that can prevent infestation of tree borers to infested trees and shrubs. Timing is crucial as it is best to treat trees early on in an infestation to attack the newly-hatched tree borer larvae before they begin tunneling into the bark.

Measure the square footage of the treatment area to help you determine how much Sylo Insecticide you need to mix. In a sprayer, dilute 0.33 to 0.65 fl. oz. per 1,000 sq.ft. in a volume of water sufficient for uniform coverage such as 3 to 20 gallons. Once you have calculated and mixed the appropriate amount of Sylo Insecticide in a sprayer, shake the sprayer well and you’re ready to treat.

Apply over the tree trunks, trigs, and branches on a fan spray setting but not to the point of runoff. If you see any holes or cavities in the wood, spray them directly via pin stream setting. You want to saturate the openings and contact as many insects as possible.

Step 2: Soil Treatment with Dominion 2L

Once the tree has been treated, we recommend a soil treatment with Dominion 2L. Dominion 2L is a systemic insecticide meaning that it when applied to the soil, it will be taken up into the tree roots and help to control any tree borer pest that tries to burrow or feast on the tree. Measure the diameter of your tree before treating.

Dilute Dominion 2L at a rate of 0.1 to 0.4 fl. oz. per inch of trunk diameter. So for example, if your trunk’s diameter is 15 inches you will need to mix 1.5 to 6 fl. oz. of Dominion 2L per 5 gallons of water. Mix it in a sprayer and apply uniformly as a drench around the base of the tree directing the application to the root area.

Prevention

After treatment has completed, tree borers should no longer be infesting your tree but you will need to make sure they do not reinfest. Here are some practices we suggest:

Replacing the tree

If the damage of the tree is quite extensive the only way to take care of the infestation is to remove the whole tree from its roots and replace it with new one. Replanting a new one and protecting it with preventive treatments of Sylo Insecticide and Dominion 2L may be the only way to control the damage.

Mulching around the tree

Place mulch, supplemental water and fertilizers around the tree at times it helps in preventing the tree borers from causing harm to the tree. This will help in controlling the damage being caused by borers. Use proper organic compost and fertilizers that are nitrogen-free. Clean up all the debris.

Pruning the trees

It is best to cut off the branches and nearby mulches, grass, and cut all the unwanted decayed leaves and branches as short and trim as possible. It will make it unappealing and more difficult for the tree borers to infest a trimmed tree.

While pruning cut off the infected branches, the crossed branches and cut the branches laterally 6 inches deep till you reach the disinfected portion of the branch. Dip cloth in alcohol and rub it all over the cuts and trunk it prevents re-infestation from occurring. Plant other flowers during winter to avoid attracting the borers and keep the borers away.

Sealing with pruning paste

Apply or fill the cuts and from the pruning with prune paste. A batch of old paint tree antiseptics, petroleum and diatomaceous earth-based products all can be used as prune paste. Sealing the saps and cuts heals the wounds of trees more quickly and prevents the tree borers from entering inside the trunk to damage the trunk.

Key Takeaways

  • Tree Borers are a destructive group of pests known to destroy wood as adults or lay eggs inside of trees where destructive larvae hatch and burrow and cause damage.
  • Using a combination of contact insecticide treatment with Sylo Insecticide and a soil drench treatment of Dominion 2L can help to eliminate tree borers from your tree.
  • Practice maintenance of your trees with pruning and mulching to prevent reinfestation. In some cases when there is extensive damage, it may be better and safer to replace the tree entirely then use the Sylo Insecticide and Dominion 2L as preventative measures to protect your new tree.

Holes in trees can be disconcerting. Many homeowners are unsure about what holes indicate for tree health, or what they should do when a hole appears. In this post, we address tree holes and talk about how a hole could be a sign of compromised structural integrity. We discuss different kinds of holes that may be found, as well as how and why they occur. Although holes are not always a sign that there is something wrong, it is best not to take chances. If there’s a hole in your tree, be sure to contact a licensed and insured Portland tree care company to learn about potential structural damage.

Are tree holes hazardous? They can be if they cause the structural integrity of the tree to fail. If this happens, the whole tree or one of its main branches may plummet to the ground, which could lead to injury and/or property damage. On the other hand, many tree holes do not present a problem, and do not necessarily need to be filled. In fact, our Portland arborists warn against filling holes with concrete (which was frequently recommended in the past), because this can actually lead to more problems.

If you are concerned about the hole for aesthetic reasons, there are foams that arborists now use to fill holes. These foams work better than concrete, as they allow more movement when the tree sways. But these foams cannot improve structural integrity; they are solely for aesthetic purposes. If there is a problem with the tree’s structural integrity, an arborist has other tools at her/his disposal, which can include cabling, bracing, propping up, or removal.

Let’s look at some common forms and causes of tree holes.

Splits and Cracks. Oftentimes a tree will form a split or crack in its trunk. Splits pose serious problems as they place stress on the structural integrity of the tree. Once a crack starts, it is likely to grow, as the tree buckles and sways in the wind. This is why it’s important to address them as early as possible. Cabling may be effective, but if the problem is too severe, you might need to remove a limb or even the entire tree. Our arborists also provide safe and effective tree removal services for split trees that can’t be salvaged.

Mushrooms and Fungi. Fungi growing at a tree’s base suggest there may be a larger problem. Hollows can also be signs of fungal infection. Since some fungi are benign, and others are harmful, it is best to let an arborists make the call and offer their expert advice.

Sapsucker and Woodpecker Holes. These destructive birds chip away at tree bark to access tree sap and resident insects. Woodpeckers and sapsuckers can do serious damage as they bore small holes in trees. While these birds don’t kill trees, their feeding can weaken them and leave them more susceptible to diseases and insect infestation.

Tree Hollows. These are often caused by fungi and can be a sign that there is decay inside the tree, which can ultimately lead to a loss of structural integrity. Squirrel holes can also be indicative of a problem.

Often a tree has holes but it is unclear if they are big enough to cause problems. Determining the structural integrity of a tree is as much an art as it is a science. Professional arborists use specialized tools to evaluate tree strength. One of these tools is called a Resistograph. It uses a small drill to test density. Trained arborists can conduct tests and carry out procedures to prevent damage and prolong a tree’s lifespan. Inspection and monitoring are key to ensuring the safety and long-term survival of the trees on your property.

Be sure to call a certified arborist today if you see evidence of structural damage or are worried about tree holes. Our ISA-certified arborists have the skills, expertise, and tools to make the right call regarding the health and well-being of your trees.

Holes in Tree Trunks

Since I have had a rash of reports about strange rows and columns of holes in trees, I thought it would be a good time to update the subject for everyone. There are those who say that holes drilled in limbs and trunks is just cosmetic and doesn’t hurt the tree. That’s incorrect on two accounts. The drilling indeed does hurt and can kill trees. Secondly, the work of these woodpeckers indicates serious stress in the trees.
The sapsucker is a bird that drills holes in rows or rings around the trunks of trees. Do they hurt anything? You bet they do. Sapsuckers are pleasant to look at but can be very destructive.
There is however a solution to their damage. When a tree is in stress, the sugars concentrate to provide nutrients to help fight infirmities and to help repair injuries. Certain animals like sapsuckers can detect that change. We know this from research at the USDA’s Northwest Forest Experiment Station. This theory is also backed up by Lawrence Kilham in his book Woodpeckers of Eastern North America.
The following are quotes from the book in the chapter on Yellow Bellied Sapsuckers – under “Relation to Wounded Trees”.
Sapsuckers feed on a wide variety of trees. Regardless of the tree utilized, it is not always clear why they concentrate on a few, leaving others untouched. In the summers of 1962 and 1963, I found three places in Lyme that seemed to provide answers. One centered on a row of paper birches bordering a dirt road and badly bruised by snow plows.
Practically all of the birches with sapsucker holes were ones with scars. Other birches of similar size and adjacent to them, but unwounded, had none. Two feeding trees stood back from the road. Although untouched by the plow, they had extensive injuries of unknown origin below their bands of drill holes.
I found sapsuckers making small bands on healthy birches nearby. These bands were at the same height as the main feeding holes, but drilling was casual, as if not more than a displacement activity.
I watched sapsuckers where hundreds of unwanted or weed trees had been girdled by foresters. Most of the trees in one area, not much affected by being girdled the previous winter, still had canopies. Trees in another region, in contrast, in a second summer after girdling, were either dead or dying by August. The dying trees were the ones that attracted the sapsuckers, which drilled just above the girdles.
The three patterns, encountered on a single species, show that the drilling of sapsuckers is related to the underlying physiology of the tree.
Sapsuckers obtain theirs by repeated wounding. This leads to an increased flow of nutrients, an effort of the tree to repair the injury that nutrients will accumulate above a girdle, as indicated by a layer of thickened wood.
Sapsucker Damage

The injury from these birds is a solvable problem. First, splash hydrogen peroxide on the wounds, then smear on Tree Trunk Goop which is one third each of compost, soft rock phosphate and natural diatomaceous earth. Then apply the Sick Tree Treatment to improve the health of the tree. As Kilham’s research would suggest, the birds will no longer be attracted to the trees.
To help keep these beautiful pests from damaging your trees in the first place, use gentle organic fertilizers only; use none of the high nitrogen synthetic stuff; make sure the soil is aerated rather than compacted; avoid physical damage to trunks and limbs; maintain the proper soil moisture, and remove the soil from the root flares. Arborists can do this work with the Air Spade or Air Knife.

The damage shown below is a different pest. The bleeding and random holes indicates borer beetle larvae.

This is borer infestation not sapsucker damage.
Applying orange oil at 50% dilution will kill the borer insects. The Sick Tree Treatment will prevent their return. Sometimes called a woodpecker, the beautiful red-headed sapsucker is lovely to look at but a real menace
The sapsucker is a bird that drills holes in rows or rings around the trunks of your trees – especially young live oaks. Do they hurt anything? You bet they do. .
When a tree is in stress, the sugars concentrate to help fight infirmities and to help repair injuries. Certain animals like the sapsucker can detect that. We know this from research at the USDA’s Northwest Forest Experiment Station. This theory is also backed up by Lawrence Kilhan in his book Woodpeckers of Eastern North America.
The birds like the sweet sap and drill the holes in tidy rows so the sap flows and is easy to suck up. Other animals will also take advantage of the sweet oozing sap, including butterflies, other birds and squirrels. To solve the problem splash some hydrogen peroxide on the wounds, then smear on some homemade Tree Trunk Goop which is one third each – compost, soft rock phosphate and natural diatomaceous earth. Then apply the Sick Tree Treatment to improve the health of the tree so the sapsucker won’t be attracted.
To help keep these beautiful pests from damaging your trees in the first place, use the gentle organic fertilizers only, none of the high nitrogen synthetic stuff, make sure the soil is aerated rather than compacted, avoid physical damage to trunks and limbs and maintain the proper soil moisture.
Here are some web sites with additional information on sapsuckers:

Sapsucker damage on ginkgo trunk.
QUESTION: I have two ornamental pear trees that are more than 17 years old. I recently noticed four rows of almost perfect holes, one row on top of the other, on one of the tree trunks. I have heard woodpecker sounds, but I also worry that I may have insect pests. G.M., Sherman
ANSWER: Sapsuckers are woodpeckers that drill holes in rows and columns. They are seeking concentrated sugars that accumulate in stressed trees.
Even if your trees look healthy, the bird damage indicates that the trees need help. Use my Sick Tree Treatment.

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