Given that it’s smaller than a grain of rice, it might be hard to believe that the minuscule southern pine beetle (Dendroctonus frontalis) could cause massive damage to forests! These beetles have been a well-known foe of the southern United States for centuries, but they are a new enemy to the Northeast.
The southern pine beetle was first recorded in the southeastern United States in the late 1700s. Though they are originally native to the southeast, warming winter temperatures have allowed the beetles range to expand up the east coast in recent decades.
Photo/Felicia Hubacz, Massachusetts Bureau of Forest Fire Control and Forestry When European settlers arrived in North America, they cut down many of the original forests that were primarily composed of trees like oak and hickory, which are naturally resistant to the southern pine beetle. With the soil quality altered from agricultural use by the settlers, pine species that are susceptible to the beetle grew back in the place of the oak and hickory. Infestations in New Jersey and New York started around a decade ago, and in 2023, there were outbreaks on Marthas Vineyard and Nantucket. Early this year, an infested tree was identified at Pilgrim Heights in the town of Truro within the bounds of Cape Cod National Seashore.
Unfortunately, it can be challenging to spot the beetles themselves, considering that they are smaller than half of a grain of rice in their adult form. The beetle looks different during each stage of its life:
Luckily, the physical appearance of the beetle isnt the only way to identify their presence, as you can tell by the damage they cause. The presence of pitch tubes would be your first physical indicator. Pitch tubes look like popcorn sticking out of the bark; these are the trees natural defense against predators. If you peel back the bark of an infested tree, you might also find S-shaped designs drilled into the wood called “galleries.”
Photo/Jiri Hulcr, University of Florida Female southern pine beetles will create these galleries to lay their eggs. The females also release pheromones to draw males to the trees. Once a tree becomes infested, it can die quickly. Often, the trees that the beetles choose are weakened ones, but that is not always the case. Southern pine beetles like to infest many trees in an area and have been known to kill acres of trees in very short periods of time. An outbreak can be very harmful for many reasons, but dangerous specifically for Cape Cod because of the Pitch Pine Barren habitat that many species rely on.
Photo/ Southern Forest Insect Work Conference Archives Southern pine beetles are often mistaken for the black turpentine beetle, a familiar insect to the northeastern United States. Black turpentine beetles are larger than southern pine beetles, measuring up to the size of a grain of rice. Their damage to trees is visually similar, but there are a few key differences. The pitch tubes they create tend to be located from the foot of the tree to about fifteen feet up, whereas southern pine beetles tend not to cause damage around the trees base. Differences in the galleries made under the bark can also indicate which species is the culprit, with the galleries of black turpentine beetles tending to be less intricate. Black turpentine beetles also do not kill acres of trees at a time, but rather one to a few sickly trees in one area.
Photo/Mississippi Entomological Museum Fortunately, we dont need to wait for an outbreak to happen to confirm the presence of southern pine beetles. Setting and monitoring traps on trees or poles are effective ways of identifying a small population of beetles before things get out of control. Lindegren funnel traps are used to monitor for the southern pine beetle. These traps consist of a series of funnels that contain a preservative like ethanol at the bottom. The funnels are strung between two trees and attract the beetles, who mistake the trap for a tree.
Photo/Ronald F. Billings, Texas A&M Forest Service, Bugwood.org Aerial and ground surveys are another technique used to detect beetles in early and later stages. Sadly, many infestations of single or small groups of trees are caught too late, which leads to an outbreak, where larger swaths of forest are impacted.
There are a few effective ways to treat a southern pine beetle outbreak. Prescribed burns, where planned fires are set and carefully managed, can combat an outbreak as well as strengthen the ecosystem in pitch pine forests.
Felling trees is another option, with a few different techniques available. The “cut and remove” technique consists of removing infected trees from the site to be processed, while “cut and leave” can be used when trees cannot be taken to a different location, so they are left where they are cut. Cutting down trees and thinning areas of forest creates more distance between trees, which makes it more difficult for the beetles to communicate via pheromones, find each other, and attack in large numbers.
Photo/John N. Cullity, Sandwich Conservation Trust The southern pine beetle will continue to be a threat to New England with the rise in average temperatures and warming weather. There are ways to combat and stop them from spreading further north, but people must be on the lookout for warning signs. Early detection is the best way to keep the beetles contained in a small area while determining a course of action for response and elimination. The southern pine beetle is a threat everyone should take seriously to protect Cape Cods Pitch Pine Barrens for generations to come.
Trees provide us with oxygen timber, shade and beauty. But sometimes, beetles can turn from being harmless tree dwellers to destructive pests that kill trees.
There are around 400,000 species of beetles that belong to the order Coleoptera. While most beetles live in harmony with their tree hosts, several types will feed on trees, damage bark, foliage and eventually kill the tree
In this article, we’ll look at 13 of the most destructive beetles that are known to kill trees worldwide.
How Do Beetles Kill Trees?
Beetles have different ways of damaging trees. Bark beetles like the mountain pine beetle will lay eggs under the bark. The larvae then tunnel and feed on the vascular tissue of the tree disrupting water and nutrient transport.
Trees weakened by drought or old age are most susceptible. Other beetles like the Asian longhorned beetle will feed on the woody parts of trees during their larval stage, while adults will chew on leaves, flowers and twigs.
Repeated attacks can girdle trees cutting off the flow of nutrients and usually result in the death of the tree.
Here are 13 of the most harmful beetles that can kill trees
1. Mountain Pine Beetle
Scientific Name: Dendroctonus ponderosae
Host Trees: Pine
Native to North America, the mountain pine beetle has destroyed over 20 million hectares of pine forests in the last two decades. Warmer winters have allowed their numbers to increase and spread.
These small black beetles lay eggs under the bark of weakened pines. The larvae feed on the living tissue, cutting off water and nutrient transport. Successful attacks lead to the death of the tree within a year.
2. Asian Longhorned Beetle
Scientific Name: Anoplophora glabripennis
Host Trees: Maple, Poplar, Willow, Elm
Native to China and Korea, the Asian longhorned beetle has become invasive in North America and Europe. Their larvae bore deep into the heartwood of hardwood trees eventually killing them.
Adults emerge through round holes, leaving behind frass. They also feed on small branches and leaves. Maples are among the most susceptible trees.
3. Spruce Beetle
Scientific Name: Dendroctonus rufipennis
Host Trees: Spruce
Spruce beetles are aggressive bark beetles that attack spruce trees in North America, especially when drought-stressed. They tunnel under the bark and damage the inner phloem layer.
Successful attacks block water and nutrient transport in the tree. Spruce trees usually die within 1-3 years of infestation by these small black beetles.
4. Walnut Twig Beetle
Scientific Name: Pityophthorus juglandis
Host Trees: Walnut
As their name suggests, these tiny beetles mainly attack walnut trees and are native to Southwestern North America. They carry a pathogenic fungus that infects the vascular tissue of walnut trees leading to thousand cankers disease.
Infested trees exhibit wilting, yellowing leaves andbranch dieback within a few years as the beetles and fungus progressively destroy the phloem.
5. Shot Hole Borer Beetle
Scientific Name: Euwallacea sp.
Host Trees: Avocado, Maple, Willow
Several invasive Euwallacea species introduce a Fusarium fungus while tunneling into trees. The fungus clogs up the vascular system leading to the dieback of branches and eventual death.
Shot holes from their entry and exit points, gumming and frass are visible signs of infestation on affected trees like avocado, maples and willows.
6. Emerald Ash Borer
Scientific Name: Agrilus planipennis
Host Trees: Ash
Accidentally introduced from Asia, emerald ash borers have already destroyed tens of millions of ash trees in North America. Their larvae feed on the inner bark effectively girdling and killing trees within 2-4 years of attack.
Adults leave distinctive D-shaped exit holes on trunks. Other signs include vertical bark splitting and excessive sprouting from the roots and trunk.
7. Elm Bark Beetle
Scientific Name: Scolytus scolytus
Host Trees: Elm
Elm bark beetles are important vectors of Dutch elm disease, caused by the Ophiostoma fungus. Adults carry fungal spores on their bodies and introduce it into trees while feeding.
The fungus spreads through the vascular tissue blocking water transport. Infected elms exhibit wilting, yellowing leaves and dieback within months.
8. Eucalyptus Longhorned Borer
Scientific Name: Phoracantha semipunctata
Host Trees: Eucalyptus
The larvae of these large beetles bore into eucalyptus trunks and branches severely damaging the vascular tissue. Gum bleeding from bore holes and exit holes are visible signs of infestation.
Trees infested by eucalyptus longhorned borers eventually dieback from the top downwards, as the larval feeding interrupts the downward flow of nutrients.
9. Pine Sawyer Beetle
Scientific Name: Monochamus spp.
Host Trees: Pine
Pine sawyer beetles transmit the pine wilt nematode to pines around the world leading to Pine Wilt Disease. The nematode clogs resin canals that transport water and nutrients within the tree.
Affected pines initially show needle discoloration and defoliation, followed by death within a few months. The beetles also bore into the sapwood but cause less damage.
10. Citrus Longhorned Beetle
Scientific Name: Anoplophora chinensis
Host Trees: Citrus, Willow, Maple
Native to Asia, these striking beetles have black bodies marked with white spots. Adults feed on leaves, while larvae bore into the branches and trunks of host trees.
Their extensive galleries and wounds make infested trees prone to snapping. Citrus, maple and willow are among the susceptible trees.
11. Redbay Ambrosia Beetle
Scientific Name: Xyleborus glabratus
Host Trees: Redbay, Avocado
Redbay ambrosia beetles act as vectors of laurel wilt, a deadly fungal disease that has devastated redbay populations in the southeastern United States.
As the fungus spreads through the vascular system, infected redbay trees wilt suddenly and die within a few weeks or months. Avocados are also susceptible host trees.
12. Balsam Woolly Adelgid
Scientific Name: Adelges piceae
Host Trees: Fir
While not a beetle, the balsam woolly adelgid is a major pest of true firs throughout North America. Feeding by nymphs causes damage that stops nutrients flowing in the vascular tissue of trees.
Infested trees exhibit discolored needles, swollen twigs and eventual dieback starting from the bottom up. Mortality often occurs within 10 years.
13. Coconut Hispine Beetle
Scientific Name: Brontispa longissima
Host Trees: Coconut, betel nut
The coconut hispine beetle is a major pest of coconut and other palms across Southeast Asia and the Pacific Islands. Adults and larvae feed on leaflets causing defoliation and reducing yield.
Heavily infested palms exhibit extensive yellowing and dieback. Seedlings often do not survive attacks by this invasive beetle.
Summary
-
Several types of aggressive bark and wood boring beetles can kill trees when they reach high infestation levels.
-
Native beetles like the mountain pine beetle and spruce beetle turn into pests when climate factors allow them to multiply to outbreak levels.
-
Invasive beetles introduced from other countries can be highly destructive to native trees which lack natural defenses.
-
Feeding and tunneling under the bark cuts off water and nutrient transport within a tree.
-
Attacked trees exhibit dieback symptoms and mortality within a few years.
-
Maintaining tree health through proper care can help prevent attacks by beetles. Catching infestations early allows for quicker control.
By understanding how different beetles impact trees and identifying early signs of infestation, you can take timely action to protect landscape trees from these destructive pests. Consult an arborist at the first signs of poor tree health.
Explore the National Park Service
The geographic range of damage from the southern pine beetle.
Map/United States Department of Agriculture and the United States Forest Service
Given that it’s smaller than a grain of rice, it might be hard to believe that the minuscule southern pine beetle (Dendroctonus frontalis) could cause massive damage to forests! These beetles have been a well-known foe of the southern United States for centuries, but they are a new enemy to the Northeast.
The southern pine beetle was first recorded in the southeastern United States in the late 1700s. Though they are originally native to the southeast, warming winter temperatures have allowed the beetles range to expand up the east coast in recent decades.
Southern pine beetle from Pilgrim Heights, Truro under a microscope.
Photo/Felicia Hubacz, Massachusetts Bureau of Forest Fire Control and Forestry When European settlers arrived in North America, they cut down many of the original forests that were primarily composed of trees like oak and hickory, which are naturally resistant to the southern pine beetle. With the soil quality altered from agricultural use by the settlers, pine species that are susceptible to the beetle grew back in the place of the oak and hickory. Infestations in New Jersey and New York started around a decade ago, and in 2023, there were outbreaks on Marthas Vineyard and Nantucket. Early this year, an infested tree was identified at Pilgrim Heights in the town of Truro within the bounds of Cape Cod National Seashore.
Life cycle of the southern pine beetle.
Graphic/Ronald F. Billings, Texas A&M Forest Service
Unfortunately, it can be challenging to spot the beetles themselves, considering that they are smaller than half of a grain of rice in their adult form. The beetle looks different during each stage of its life:
- The egg is white.
- The larva is crescent-shaped with a dark red/brown head.
- The pupa is white.
- As an adult, they are light brown/black.
Popcorn-like pitch tubes on an affected tree.
Photo/Jiri Hulcr, University of Florida
Luckily, the physical appearance of the beetle isnt the only way to identify their presence, as you can tell by the damage they cause. The presence of pitch tubes would be your first physical indicator. Pitch tubes look like popcorn sticking out of the bark; these are the trees natural defense against predators. If you peel back the bark of an infested tree, you might also find S-shaped designs drilled into the wood called “galleries.”
Southern pine beetle galleries drilled under the bark of the tree tend to look like complex mazes.
Photo/Jiri Hulcr, University of Florida Female southern pine beetles will create these galleries to lay their eggs. The females also release pheromones to draw males to the trees. Once a tree becomes infested, it can die quickly. Often, the trees that the beetles choose are weakened ones, but that is not always the case. Southern pine beetles like to infest many trees in an area and have been known to kill acres of trees in very short periods of time. An outbreak can be very harmful for many reasons, but dangerous specifically for Cape Cod because of the Pitch Pine Barren habitat that many species rely on.
A southern pine beetle (left) and a black turpentine beetle (right) compared to a grain of rice (middle) in someone’s palm.
Photo/ Southern Forest Insect Work Conference Archives Southern pine beetles are often mistaken for the black turpentine beetle, a familiar insect to the northeastern United States. Black turpentine beetles are larger than southern pine beetles, measuring up to the size of a grain of rice. Their damage to trees is visually similar, but there are a few key differences. The pitch tubes they create tend to be located from the foot of the tree to about fifteen feet up, whereas southern pine beetles tend not to cause damage around the trees base. Differences in the galleries made under the bark can also indicate which species is the culprit, with the galleries of black turpentine beetles tending to be less intricate. Black turpentine beetles also do not kill acres of trees at a time, but rather one to a few sickly trees in one area.
Lindegren funnel traps are an excellent way to monitor for the beetle, but must be checked regularly.
Photo/Mississippi Entomological Museum Fortunately, we dont need to wait for an outbreak to happen to confirm the presence of southern pine beetles. Setting and monitoring traps on trees or poles are effective ways of identifying a small population of beetles before things get out of control. Lindegren funnel traps are used to monitor for the southern pine beetle. These traps consist of a series of funnels that contain a preservative like ethanol at the bottom. The funnels are strung between two trees and attract the beetles, who mistake the trap for a tree.
Aerial view of an outbreak, where large patches of trees are dying.
Photo/Ronald F. Billings, Texas A&M Forest Service, Bugwood.org Aerial and ground surveys are another technique used to detect beetles in early and later stages. Sadly, many infestations of single or small groups of trees are caught too late, which leads to an outbreak, where larger swaths of forest are impacted.
Thinning of pine stands is a management technique used to combat the southern pine beetle throughout the United States. This sign indicating that the forest has been thinned to prevent southern pine beetles is located in Virginia.
Photo/ Katlin Dewitt, Virginia Department of Forestry
There are a few effective ways to treat a southern pine beetle outbreak. Prescribed burns, where planned fires are set and carefully managed, can combat an outbreak as well as strengthen the ecosystem in pitch pine forests.
Felling trees is another option, with a few different techniques available. The “cut and remove” technique consists of removing infected trees from the site to be processed, while “cut and leave” can be used when trees cannot be taken to a different location, so they are left where they are cut. Cutting down trees and thinning areas of forest creates more distance between trees, which makes it more difficult for the beetles to communicate via pheromones, find each other, and attack in large numbers.
The pitch pine habitat on Cape Cod will need to be protected from the destructive southern pine beetle to survive.
Photo/John N. Cullity, Sandwich Conservation Trust The southern pine beetle will continue to be a threat to New England with the rise in average temperatures and warming weather. There are ways to combat and stop them from spreading further north, but people must be on the lookout for warning signs. Early detection is the best way to keep the beetles contained in a small area while determining a course of action for response and elimination. The southern pine beetle is a threat everyone should take seriously to protect Cape Cods Pitch Pine Barrens for generations to come.
You can help keep our forests safe by following these guidelines:
- Be on the lookout! If you see a tree displaying symptoms of southern pine beetle infestation, like pitch tubes, contact the Massachusetts Department of Conservation Forestry Health program to report the tree. Massachusetts Southern Pine Beetle Reporting Form
- Make sure you are not bringing in firewood to campsites and bonfires from elsewhere. Use local firewood instead!
Southern pine beetles killing thousands of trees across Long Island
FAQ
What kind of beetle kills trees?
The Southern Pine Beetle: The Tree Killer. The geographic range of damage from the southern pine beetle.Nov 8, 2024
How do you get rid of tree eating beetles?
Proper application involves thoroughly drenching the main trunk, exposed root collar near the base of the tree, and larger branches (for engraver beetles) …
Are tree beetles harmful?
Like emerald ash borers, bark beetles tunnel under bark and devour nutrients from the trunk that would normally help the tree grow and thrive. There are 600 types of bark beetles, which puts many kinds of trees in danger. However, they seem to target fir, pine, cedar, and spruce trees most often.
Can you save a tree with pine beetles?
These insects don’t harm the tree. They seek out trees that are dying or already dead. They are found in conifer trees. Treatments are not needed. The best thing you can do is keep your trees as healthy as possible. If possible, consider supplemental water all year around when we have long periods of dry weather.
Can beetles kill pine trees?
When it comes to beetles that can kill pine trees, there are two main culprits: bark beetles and ambrosia beetles. Bark beetles feed on the inner bark of pine trees, weakening it and eventually killing the tree. Ambrosia beetles, on the other hand, bore into the wood of the tree, causing it to rot and eventually die.
Do beetles kill trees?
They do play a role in forest life, where they attack older and weakened trees. This speeds the development of younger trees. This beetle lays eggs under the bark of the tree, which introduces a blue stain fungus into the sap, preventing the tree from killing the beetle. The fungus blocks water and nutrient transport inside the tree.
What pests kill pine trees?
Other pests that can attack and kill pine trees include pine sawflies and wood-boring beetles. Pine sawflies are small insects that feed on the needles of pine trees, eventually killing them. Wood-boring beetles are beetles that feed on the wood of pine trees, causing them to rot and eventually die.
Do Bark beetles attack trees?
Because there are SO many different types of bark beetles, it seems there’s a bark beetle out there for nearly every tree type. But, primarily, bark beetles attack cedar, fir, pine and spruce trees. There are some beetles out there that go after arborvitae, cypress, elm, fruit, larch and redwood trees.
Do pine trees eat bark beetles?
Fortunately, there are several management strategies that can be used to protect pine trees from these pests. Bark beetles are one of the most common pests that can kill pine trees. These beetles feed on the inner bark of the tree, causing it to become weakened and eventually die.
What are beetle kill pine products?
Commonly purchased beetle kill pine products include siding, flooring, paneling, furniture, doors, cabinets, and moulding. We can lessen the severity of this epidemic with proper forest management, salvaging beetle killed pine trees, and reducing forest fuels.