How to Get Rid of Powderpost Beetles
The following points will help discourage powderpost beetle infestations:
- 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.
- 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.
- Don't store valuable items in sheds and barns. Wood boring beetles are common in these areas.
- Infested furniture that is unfinished (unvarnished, not painted, not waxed or not sealed) can be treated with Tim-bor or Boracare. Boracare or Timbor will prevent newly hatched larvae from entering the wood. Infested furniture that can not be treated with a product like Tim-bor or 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.
- If practical, remove infested wood. If not, use residual borate insecticides such as Boracare or Timbor.
- 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.
- 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.
Inspection For Wood Boring Beetles
| (Click on images to enlarge |
Photos courtesy of IPM Alabama)
- 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.
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)
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 Power post 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.
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.
Click to Enlarge
- 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.
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.