Orangish-coloured insect living in wood chips

Orangish-coloured insect living in wood chips

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Can anyone Identify this organism?

I dug it up in a pile of 5 year old wood chips in Cleveland, Tennessee, United States. It is about 4 inches long.

That is the pupa of a unicorn beetle, Dynastes tityus.

The cardboard controversy

I’m not a fan of using corrugated cardboard as a mulch, which like other sheet mulches creates problems for the underlying soil. Long-time readers of this blog may remember several previous posts (1, 2, 3 and 4) on this topic and I won’t belabor the points made in those posts. Instead, today I’m doing to focus on cardboard itself.

Cardboard mulch under wood chips

First, cardboard is a generic term that can refer to many types of manufactured paper. The box you see delivered to your front door is more properly called corrugated board or containerboard. It consists of two layers of linerboard sandwiching a layer of accordion-like fluting material. The linerboard is made from sheets of pulp that may be coated to improve smoothness (more about this later). The finished linerboard is laminated using adhesives to both sides of the fluting material.

Corrugated boxes are built tough

These boxes are made to withstand rough handling and to protect the contents from the external environment. It’s tough stuff: while you might be able to bend a piece of corrugated board fairly easily, it’s more difficult to tear it in half. The more heavy duty the box, the more difficult it is to bend or tear its walls.

So let’s now consider using this tough material in your garden as a mulch. It may be coated as mentioned earlier to improve smoothness. That’s going to prevent it from absorbing moisture. The coating also reduces the ability for gases to move between the soil and the atmosphere. In fact, smoothness is measured using an air leak method – the smoothest materials have the least air leakage.

Photo credit: vizpix at Flickr

A garden or landscape mulched with cardboard (or heaven forbid several layers of cardboard as part of the science-free lasagna mulch method) is now covered with a tough, relatively gas- and water-impermeable material that will take some time to break down. It’s hardly a mulch that’s going to nurture soil life.

But cardboard mulch fans swear that they find more earthworms under cardboard than anywhere else in their garden. This is almost always the first response I get from gardeners who don’t believe that cardboard causes problems. And this is where it’s important to consider earthworm behavior.

Photo credit: Kurt B. on Flickr

We’ve all observed that earthworms crawl to the soil surface during heavy rains this is due in part to water filling their burrows and reducing oxygen availability (Chuang and Chen demonstrated this nicely in 2008). Likewise, the reduction in oxygen movement from the atmosphere into cardboard-covered soil would cause worms to crawl upwards in an effort to find oxygen at the soil surface.

So don’t assume your lasagna mulching draws earthworms to your garden. It’s more likely that you’re smothering their habitat.

***An update on cardboard gas permeability. We’ve just published an article comparing diffusion rates of different mulches. You can find the article here but it is behind a paywall. Here is a graphic comparing diffusion rates of various mulches. This is a logarithmic scale.
Now, until cardboard proponents publish evidence to the contrary, it’s pretty obvious that cardboard mulch interferes with gas diffusion.

***And another update on how our blog works. This post, by far, is the most popular. It generates a lot of comments. All comments must be approved before they’re posted, and I don’t approve comments that are derogatory or promote a belief in the absense of supporting science. If you want your comment to be published, be polite and provide evidence to support your statements. Otherwise, you are wasting your time.

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Nest Placement

Northern Flickers usually excavate nest holes in dead or diseased tree trunks or large branches. In northern North America look for nests in trembling aspens, which are susceptible to a heartrot that makes for easy excavation. Unlike many woodpeckers, flickers often reuse cavities that they or another species excavated in a previous year. Nests are generally placed 6-15 feet off the ground, but on rare occasions can be over 100 feet high. Northern Flickers have been known to nest in old burrows of Belted Kingfishers or Bank Swallows.

Nest Description

Both sexes help with nest excavation. The entrance hole is about 3 inches in diameter, and the cavity is 13-16 inches deep. The cavity widens at bottom to make room for eggs and the incubating adult. Inside, the cavity is bare except for a bed of wood chips for the eggs and chicks to rest on. Once nestlings are about 17 days old, they begin clinging to the cavity wall rather than lying on the floor.

Nesting Facts

Naked, pink skin, a sharp egg tooth at the tip of bill eyes closed, movements clumsy.


Carpenter ants damage wood by excavating and creating galleries and tunnels for their nest. These areas are clean, do not contain sawdust or other debris, and are smooth with a well-sanded appearance.

The damage to wood structures is variable. The longer a colony is present in a structure, the greater the damage that can be done. Structural wood can be weakened when carpenter ant damage is severe. Generally, damage occurs slowly, often taking years to occur.

Prevention and control

To prevent carpenter ant problems indoors, eliminate high moisture conditions.

  • Replace moisture-damaged wood.
  • Prevent moisture from wood or lumber that is stored in a garage or near the house by elevating it to allow air circulation.
  • Store firewood as far away from buildings as possible.
  • Remove tree and shrub stumps and roots.
  • Trim branches that overhang the home, so branches don't touch the house (including roof and eaves).
  • Prune branches that touch electrical lines. Carpenter ants can travel from branches to lines and use them to get into buildings.

How to find carpenter ant nests

In order to eliminate carpenter ants nesting indoors, you need to locate and destroy their nest. This is often challenging as nests are hidden and not easily discovered. Careful observations of worker ants will help you find the nest. Observe worker ants between sunset and midnight during spring and summer months.

  • Use a flashlight with a red film over the lens. Ants cannot see red light and won’t be disturbed by it.
  • Or cover part of the flashlight with your hand so it is less bright to follow carpenter ants.

You can increase your chances of following workers to their nest by setting out food that they like. Many foods are attractive to carpenter ants.

  • During spring, carpenter ants are particularly attracted to protein sources, such as tuna packed in water. (They don't like tuna packed in oil.)
  • Set out small pieces of tuna for the ants to take back to their nest. It is easier to follow the ants when they are carrying food.
  • Place food close to where carpenter ants are active so they can easily find it.

Carpenter ants are attracted to honey and other sweet foods.

Other signs that indicate a carpenter ant nest is present:

  • Finding coarse sawdust.
  • Consistent indoor sightings of large numbers of worker ants (20 or more).
  • Large numbers of winged ants indoors (late winter through spring).

Examine areas where steady moisture is or has been a problem. These are a few common locations:

  • Firewood stored in an attached garage, next to the foundation, along an outside wall, or in a basement.
  • Areas around the plumbing or vent entrances.
  • Trees with branches overhanging and touching the house or contacting utility wires.

Pest management professionals may use a moisture meter to find areas prone to carpenter ants.

Listen for sounds that may indicate a nest:

  • An active colony may make a dry, rustling sound that becomes louder if the colony is disturbed.
  • Tap the suspected area and press an ear to the surface to hear any sound.

Pest management professionals may use a stethoscope to locate a nest.

If one nest is found, there may be more nests in a structure.

Indoor control of carpenter ants

The best way to control carpenter ants is to locate and destroy the nest, replace damaged or decayed wood, and eliminate any moisture problems.

Eliminating a carpenter ant nest can be difficult because of the hidden nature of the nest. Carpenter ant control is usually best done by an experienced pest management professional. They have the experience, equipment and a wider array of products to more effectively control a carpenter ant problem.

You can help by telling the pest management professional about when, where and how many ants you've seen.

There can be more than one nest in a building, but only treat nests that have been discovered.

Indoor treatment with dust or liquid pesticides

Spraying foraging workers is not effective. It may temporarily reduce the number of ants you see. However, this will not eliminate a nest because:

  • Ants carry very little insecticide back to their nests.
  • Most ants forage outside and do not come in contact with the insecticides.
  • Only a relatively small percentage of a colony's population is out foraging at any given time.

Nests are often hidden in wall voids, ceilings, subfloors, attics or hollow doors. It is sometimes necessary for a professional pest management applicator to drill small (about 1/8 inch) holes and apply insecticidal dust into the nest area. Don't do this yourself.

Determine the nest's location as specifically as possible. Control should not be applied randomly through the home.

If the nest is exposed (for instance due to remodeling or reroofing), you can use a liquid or aerosol ready-to-use insecticide.

Other information

A number of biotic agents act as natural controls for wood borers of hardwoods. Studies have shown that birds, particularly woodpeckers, may feed on up to 75% of a population of wood borers and are probably the most effective natural control agent. Parasitic insects, especially parasitic wasps, also feed on wood borers. In the United States, fast-growing wood decay fungi have been documented as trapping pupae within feeding tunnels, thus preventing adult emergence.

Most of the wood borers prefer wounds and scars on trees for oviposition. Care should, therefore, be taken when working on or near ornamental hardwoods, because careless cultivation, pruning, or mowing may cause injury resulting in oviposition sites. Ornamental trees that are healthy and growing well are most resistant to wood borer attacks. During drought, trees should be watered to prevent the drought stress that may predispose trees to wood borer attacks.

Spiders are among most effective predators of plant pests

This undated photo shows a Black Widow spider taken in a shed near New Market, Va. Spiders are one of the gardeners best tools for biological pest control and also are one of the few pest predators that don't eat plants. (Dean Fosdick via AP)

Although many people have a built-in aversion to them, spiders rank as one of the gardener's best tools for biological pest control.

They also are one of the few pest predators that don't eat plants.

"Spiders eat the (equivalent insect) weight of all the humans on earth annually," said Linda Rayor, an assistant professor of entomology at Cornell University. "A significant percentage of those insects are herbivores or granivores (seed eaters) or other insects that adversely affect humans. Spiders perform a vital function."

There are more than 45,500 known spider species around the world, divided into 110 spider families, Rayor said.

"Few of those have a venom that affects us," she said. "The yellow sac spider, the black widow and the recluse. That's about it. And none are aggressive."

Spiders, including black widows, respond to movements in their webs, and that leads to people getting bitten, Rayor said.

"Black widows are super common in the desert around the U.S. but you'll also find them in many cities because they have water," she said. "Houses and edges of houses are perfect for black widows. They can build underneath and protect their webs."

Spiders use venom to kill or paralyze their prey. They actively hunt or spin webs to trap insects, invertebrates, and even small vertebrates like lizards and frogs. What also makes them garden-friendly is that that they don't eat plants, Rayor said.

"They'll eat a little pollen, maybe, but that's about it," she said. "They're totally beneficial to have in the garden."

This spider photographed on Sept. 11, 2015, while spinning a web in a Langley, Wash., yard, is one of the gardeners best tools for biological pest control. Spiders also are also one of the few pest predators that don't eat plants. (Dean Fosdick via AP)

On the unfavorable side, spiders are generalists in what they hunt and cannibalistic. They feed on other spiders and many beneficial insects, including honeybees and butterflies.

Spiders also are not a good choice for taking out specific plant pests in fields or gardens if there's a particular outbreak you're trying to eradicate, Rayor said. "But for reducing all prey abundance in certain areas, they're great."

Rather than try to eliminate spiders in or near homes, the knowledgeable, organic-leaning gardener prefers to recruit them.

You can increase spider numbers in the garden by:

— Adding more trees, shrubs and perennials to provide anchor points for web-building spiders to spin their webs, said Gail Langellotto, an entomologist with Oregon State University's Extension Service.

— Allowing areas to go untilled, or leaving plant stalks standing for overwintering habitat. Many adult spiders emerge in early spring, before most other bio-control resources are available.

— Mulching with grass or wood chips to provide cover and humidity.

— Growing flowers that attract insect prey.

"Even if you want to bring spider numbers down around your property, consider that they're difficult to eradicate with pesticides," Langellotto said.

"The amount and concentration needed is often higher than what's necessary to kill insects, (and that) poses a greater risk to humans," she said. "Heavy doses also will kill a lot of other beneficial insects."

Damage and Sysmptoms

Xyleborus glabratus is the only known vector of R. lauricola (Crane et al. 2008, Fraedrich et al. 2008). Trees attacked by X. glabratus exhibit few external symptoms initially. Small strings of compacted sawdust protrude from the bark at the point of attack however, these strings disintegrate easily and are not always readily apparent. Removal of bark at the point of attack reveals shot-holes from which a dark stain extends into the surrounding xylem. Initial attacks introduce spores of the fungus into the xylem of the host tree. The fungal infection is visible by stained sapwood upon removal of bark or in cross sections of the stem. The stain is the tree's response to fungal infection that gradually spreads through the outer sapwood.

Trees infested with laurel wilt are characterized by a dark discoloration in the outer sapwood. Affected trees exhibit wilted foliage with a reddish or purplish discoloration. Foliar discoloration may occur within a section of the crown or the entire crown. The foliage eventually turns brown and tends to remain on the branches (Fraedrich et al. 2008). In redbay, the fungus moves rapidly through the xylem, plugging the flow of water and causing the trees to die within few weeks or months.

New insights into biomass breakdown provided by scientists

Scientists at the University of York are playing a key role in the quest for a better understanding of how a recently discovered family of enzymes can degrade hard-to-digest biomass into its constituent sugars.

The enzymes -- lytic polysaccharide monooxygenases (LPMOs) -- are secreted by both fungi and bacteria and have the ability to 'chip away' at cellulose and other intractable materials. This allows cellulosic materials such as plant stems, wood chips and cardboard waste, as well as other tricky polysaccharides such as insect/crustacean shells, to be broken down.

Finding a way of breaking down cellulosic materials into their constituent sugars to allow them to be fermented through to bioethanol is a key aim for second-generation biofuel development.

In a recent article in the Proceedings of the National Academy of Sciences (PNAS), an international team of researchers, including Professor Paul Walton and Professor Gideon Davies from York, provided important new information on how LPMOs work.

The team -- which included scientists from the United States, Denmark and the UK -- carried out a detailed investigation of how the enzymes use oxygen from the air to create a very reactive entity. This oxygen species then chips away at cellulose, allowing the difficult-to-degrade biomass to be broken down.

The on-going York research into LPMOs, which is led by Professor Walton and Professor Davies from the Department of Chemistry, is part of Critical Enzymes for Sustainable Biofuels from Cellulose (CESBIC), a collaborative project funded by the European Research Area Industrial Biotechnology network (ERA-IB).

Professor Walton said: "The ability to ferment cellulose is important as it opens up new possibilities in the production of bioethanol from sustainable sources. Through our collaborative research we are starting to uncover exactly the details of how LPMOs work."

The recent research published in the PNAS article, builds on work reported earlier this year in Nature Chemical Biology, which was led by York, and involved Professor Bernard Henrissat, of CNRS, Aix-Marseille Université, Marseille, France. The Nature Chemical Biology article reported on the discovery of an important new family of LPMO able to break down hard-to-digest biomass. This work is funded by the Biotechnology and Biosciences Research Council (BBSRC).

Professor Davies said: "To begin fermenting materials such as wood chips or plant stems, there needs to be a way of breaking into it. The action of an LPMO makes a scratch on the biomass surface which provides an entry point for other enzymes. Understanding how LPMOs work will aid the quest for second generation biofuel production."

Worm Castings

The single greatest thing you can do for your soil is to introduce biology, and we would like you to think about soil like your gut. Without the right microbes in your gut, you do not digest even the highest quality food. In a similar vein, without the right biology in your soil, your plants cannot reach their genetic potential.

We offer two different types of worm castings or vermicompost, bacterially dominant, and fungally dominant and all of our castings include the use of locally produced BC biochar a key to producing a superior worm casting.

Our fungally dominant worm castings start out life as a local waste stream of wood chips and leaves from tree trimmers and the waste stream from the River Crest Homesteads chickens and goats and spend a total of 12 months breaking down and building a fungally dominant community of microbes before they spend their final 3 months in our a worm digester with a proprietary plethora of organic ingredients to ensure the worms and microbes have access to the full spectrum of nutrients needed to produce a top shelf premium grade worm casting.

Our bacterially dominant worm castings are also made from all organic local waste streams consisting of vegetable waste from our market garden lab and from local restaurants and are produced using the Hungry Bin where they spend about 3 months digesting in this flow through style system.

Orangish-coloured insect living in wood chips - Biology

Ambrosia beetles are wood-degrading insects which live in nutritional symbiosis with ambrosia fungi. Typically, ambrosia beetles are considered beneficial because they accelerate the decay of dead trees, which is important for nutrient cycling in healthy forests. The redbay ambrosia beetle, Xyleborus glabratus Eichhoff and its fungal symbiont, Raffaelea sp., are new introductions into the southeastern United States. Xyleborus glabratus was first detected in 2002 and is one of the 10 ambrosia beetle species in the U.S. (Haack 2003, 2006). The beetle transmits the causal pathogen of laurel wilt disease among plants in the Laurel family (Lauraceae), which is caused by one of its fungal symbionts, Raffaelea lauricola (Mayfield and Thomas 2006, Fraedrich et al. 2009). The Xyleborus glabratus and Raffaelea lauricola complex is considered a very high risk invasive disease pest complex having potential equal to that of Dutch elm disease or chestnut blight (Global Invasive Species Database 2010). Laurel wilt is a relatively new disease and much is still unknown about how it will impact the flora of North America.

Distribution (Back to Top)

Xyleborus glabratus is native to India, Japan, Myanmar and Taiwan (Rabaglia 2008). In the U.S., Xyleborus glabratus was first detected in a survey trap near Port Wentworth, Georgia in 2002 (Rabaglia 2008). In Florida, Xleborus glabratus was first detected in 2005 at the Timucuan Ecological and Historic Preserve in northern Duval County (Mayfield and Thomas 2006). Currently, the redbay ambrosia beetle is an economically important pest in Florida, Georgia and South Carolina. Recently, the beetle was detected in Jackson County, Mississippi (Riggins et al. 2010) Mobile County, Alabama (Alabama forestry commission 2010) and Bladen County, North Carolina (R. Trickel unpublished results). The pest continues to expand rapidly to new areas posing a threat to redbay and avocado trees in the U.S. and in the countries of Central and South America.

Description (Back to Top)

Adult: The adult Xleborus glabratus is a small, elongate, cylindrical beetle about 2 mm in length. It is very similar in appearance to other ambrosia beetles (both native and exotic) already found in the U.S. The combination of its blackish coloration, nearly glabrous upper surface, V-shaped and pointed abdominal tip, and abrupt apical declivity distinguishes this species from other ambrosia beetles occurring in Florida (Mayfield and Thomas 2006). However, expert examination by a specialist is needed for positive identification and confirmation. Males are dwarfed, haploid, flightless, and rarely encountered (Rabaglia 2008).

Figure 1. Dorsal view of an adult female redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Lyle J. Buss, University of Florida.

Figure 2. Lateral view of an adult female redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Lyle J. Buss, University of Florida.

Figure 3. Dorsal view of an adult male redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Lyle J. Buss, University of Florida.

Figure 4. Lateral view of an adult male redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Lyle J. Buss, University of Florida.

Figure 5. Eggs of the redbay ambrosia beetle, Xyleborus glabratus Eichhoff, inside gallery which an adult female constructed. Photograph by Lyle J. Buss, University of Florida.

Larva: The larva of Xyleborus glabratus is similar to other scolytid beetles. It is a white, c-shaped, legless grub with an amber-colored head capsule (Rabaglia 2008).

Figure 6. Larvae of the redbay ambrosia beetle, Xyleborus glabratus Eichhoff, inside galleries which adult females constructed. Photograph by Lyle J. Buss, University of Florida.

Figure 7. Two newly emerged (exoskeleton still darkening) adult redbay ambrosia beetles, Xyleborus glabratus Eichhoff, near a white pupa (bottom right) from which the adult has not yet emerged. Photograph by Lyle J. Buss, University of Florida.

Biology (Back to Top)

Currently, very little is known about the life cycle and biology of Xleborus glabratus. However, it is presumed that its biology is similar to that of other species in the Xyleborini (Mayfield and Thomas 2006). Adult females bore into the wood just below the bark and construct galleries in the sapwood, inoculating the galleries with a fungus (Rabaglia 2008, Mayfield and Thomas 2006). Most of the life cycle including mating, egg laying and larval development is completed within these galleries. The adults and larvae feed on fungi and not on the wood of the damaged host plant (Rabaglia 2008). Adults are active throughout the year with peak activity in early September (Hanula et al. 2008). In Asia, the beetle has been reported to survive in temperatures ranging from -26 to 15°C. The flight activity is greatest late afternoon or early evening and the beetles usually fly at or below 15 ft (G. Brar unpublished results).

Figure 8. Life cycle of the redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Top row, left to right: egg 1st, 2nd and 3rd instar larvae, pupa. Bottom row, left to right: the first three adults are females with progressively darkening exoskeltons, the final adult is a male. Photograph by Lyle J. Buss, University of Florida.

Most native ambrosia beetles attack only dead and dying trees. However, Xleborus glabratus initiates attacks on healthy redbay trees. The beetles drill through the bark and inoculate tree xylem with their symbiotic fungi, Raffaelea lauricola. The beetle carries the fungus in mandibular mycangia (specialized sacs above mandibles adapted for fungus transport). After becoming infected, redbays wilt within weeks to a few months. The dying tree is also colonized by numerous other ambrosia beetle species, including Xleborus affinis, Xleborus ferrugineus, Xyleborinus saxeseni and Xylosandrus crassiusculus which further inoculate the tree with their associated fungi (J. Foltz unpublished results). Beetles reproduce within their galleries and newly emerging females fly in search of new hosts. In the southeast, there could be multiple overlapping generations per year (Global Invasive Species Database 2010). The brood development occurs within 50&ndash60 days (Hanula et al. 2008, G. Brar unpublished results).

Both haplo-diploidy and inbreeding is common in ambrosia beetles including Xleborus glabratus. Females lay both diploid and haploid eggs. The more prevalent diploid eggs develop into females whereas males hatch from unfertilized haploids eggs. Therefore, males are haploid and flightless clones of their mothers with 50% of her genetic material. The males spend most of their life inside the natal gallery fertilizing their own sisters. Such sons allow single females to establish successful populations in non-native locations (Kirkendall 1983).

Hosts (Back to Top)

The host range of Xleborus glabratus includes plants in the Dipterocarpaceae, Fagaceae, Fabaceae and Lauraceae families in Southeast Asia (Rabaglia et al. 2006).

The complete host range of Xleborus glabraus in the U.S. is unknown. However, all investigated American members of the Lauraceae family have been found susceptible to the disease (Ploetz and Peña 2007). The hosts of Xleborus glabartus and laurel wilt in the U.S. include:

  • avocado, Persea americana
  • California bay laurel, Umbellularia californica
  • northern spicebush, Lindera benzoin
  • redbay, Persea borbonia
  • sassafras, Sassafras albidum
  • swampbay, Persea palustris

(Rabaglia et al. 2006, Smith et al. 2009)

The laurel wilt fungus has also been found on two critically endangered shrubs in Florida:

The beetle also feeds on camphor tree, Cinnamomum camphora, which is listed as a Category I invasive species by the Florida Exotic Pest Plant Council. However, the camphor tree is not on the Federal or State noxious weed list (Florida Exotic Pest Plant Council 2011).

Damage and Symptoms (Back to Top)

Xyleborus glabratus is the only known vector of Raffaelea lauricola (Crane et al. 2008, Fraedrich et al. 2008). Trees attacked by Xleborus glabratus exhibit few external symptoms initially. Small strings of compacted sawdust protrude from the bark at the point of attack however, these strings disintegrate easily and are not always readily apparent. Removal of bark at the point of attack reveals shot-holes from which a dark stain extends into the surrounding xylem. Initial attacks introduce spores of the fungus into the xylem of the host tree. The fungal infection is visible by stained sapwood upon removal of bark or in cross sections of the stem. The stain is the tree's response to fungal infection which gradually spreads through the outer sapwood.

Figure 9. Small strings of compacted sawdust, protruding from the bark at the point of attack, are an indication of an infestation by the redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Michael Flores, University of Florida.

Figure 10. Stained sapwood is an indication of an infestation by the redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Michael Flores, University of Florida.

Trees infested with laurel wilt are characterized by a dark discoloration in the outer sapwood. Affected trees exhibit wilted foliage with a reddish or purplish discoloration. Foliar discoloration may occur within a section of the crown or the entire crown. The foliage eventually turns brown and tends to remain on the branches (Fraedrich et al. 2008). In redbay, the fungus moves rapidly through the xylem, plugging the flow of water and causing the trees to die within few weeks or months.

Figure 11. Wilted foliage, with a reddish or purplish discoloration, caused by an infestation of the redbay ambrosia beetle, Xyleborus glabratus Eichhoff. Photograph by Michael Flores, University of Florida.

Spread (Back to Top)

Xleborus glabratus is presumed to have been introduced into the U.S. through solid wood packing materials (Fraedrich et al. 2007). The cryptic nature of ambrosia beetles makes them difficult to detect in shipments of trees or wood products (Oliver and Mannion 2001, Rabaglia et al. 2006, Koch and Smith 2008). Local spread of beetles is potentially caused by the transport of fuel wood, tree trimmings, and other infested wood products (Rabaglia 2008). Barbecue smoke-wood may also serve as a potential vehicle for moving the beetle and the fungus into new areas. The natural rate of movement of the Xleborus glabratus-laurel wilt complex within forests is estimated up to 34 miles per year (Koch and Smith, 2008). The actual spread could be even faster, especially when aided by human transport. The beetle is attracted to volatiles naturally emitted by living trees, severed limbs, tree stumps, and pruned trees of avocado, Persea americana, and redbay, Persea borbonia (Hanula et al. 2008). Female beetles are believed to be capable of flying 2&ndash3 km in search of a host (Rabaglia 2008).

Management (Back to Top)

Currently, there are no methods for preventing further infestation of susceptible trees where redbay ambrosia beetle is established. In Florida trees with signs of rapid wilting, dieback, and insect boring in redbay and other host trees should be reported to the Florida Department of Agriculture and Consumer Services' Division of Plant Industry or Division of Forestry.

To avoid spreading the beetle and pathogen to new areas, redbay and other hosts of redbay ambrosia beetle should not be moved or sold as firewood, tree trimmings, or barbecue smoke-wood. Wood from infested trees should not be transported out of the local area where the infested trees are detected. Dead redbay or other Lauraceous tree species cut in residential areas should be chipped and left onsite as mulch, or disposed of as locally as possible. The pathogen does not survive in the mulched wood chips (Crane et al. 2011).

Manuka oil, the essential oil extracted from Leptosperum scoparium and Phoebe oil, an extract of Brazilian walnut (Phoebe porosa) are potent attractants of Xleborus glabratus. Both oils are effective baits for monitoring Xleborus glabratus populations (Hanula and Sullivan 2008).

Chemical control of X. glabratus through aerial sprays is complicated and impractical because adult beetles must be in the immediate area that is treated. Once adult beetles bore into trees, contact insecticides are ineffective. For management of the vector and pathogen in avocado groves, growers should maintain tree health by preventing plant stress caused by abiotic and biotic factors. Ambrosia beetles are known to attack trees suffering from some type of environmental or cultural stress (drought, flooding, freezing, nutrient deficiencies, etc.). Avocado trees with confirmed disease symptoms should be removed to prevent spread of the vector and pathogen (Cameron et al. 2008, Hanula et al. 2008). The infested wood should be burnt within the infested grove without transportation (Crane, 2009). Avocado trees not showing symptoms but present adjacent to trees with confirmed symptoms of disease may be treated with contact insecticides to kill flying beetles (Crane et al. 2011). Damaged or pruned avocado wood is more attractive to X. glabratus than non-damaged wood for up to three weeks. Therefore, groves should be pruned during the late fall or winter when X. glabratus activity is low. Groves should be pruned early in the morning and the cut surfaces should be treated with contact insecticides with residual activity (Crane et al. 2011).

Selected References (Back to Top)

  • Alabama Forestry Commission. (November 2010). Redbay ambrosia beetle. (no longer online).
  • Cameron, RS, Bates C, Johnson J. (September 2008). Distribution and spread of laurel wilt disease in Georgia: 2006&ndash08 survey and field observations. Georgia Forestry Commission. U.S. Forest Service. (29 April 2019).
  • Crane JH. (March 2009). Issues concerning the control of the redbay ambrosia beetle (Xyleborus glabratus) and spread of the laurel wilt pathogen (Raffaelea lauricola). (29 April 2019).
  • Florida Exotic Pest Plant Council. (2011). Florida EPPC's 2009 Invasive Plant Species List. (29 April 2019).
  • Fraedrich SW, Harrington TC, Rabaglia RJ. (2007). Laurel wilt: a new and devastating disease of redbay caused by a fungal symbiont of the exotic redbay ambrosia beetle. Newsletter of the Michigan Entomological Society 52: 15-16.
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Authors: Rajinder Mann, University of Florida Jiri Hulcr, North Carolina State University Jorge Peña and Lukasz Stelinski, University of Florida
Photographs: Lyle J. Buss and Michael Flores, University of Florida
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-491
Publication Date: April 2011. Latest revision: April 2014. Reviewed April 2019.

An Equal Opportunity Institution
Featured Creatures Editor and Coordinator: Dr. Elena Rhodes, University of Florida

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