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                   Powder-post Beetles in Buildings

                         What to Do About Them


                  by R. A. St. George and T. McIntyre




                          POWDER-POST BEETLES

                            _in Buildings_

                         what to do about them

                            [Illustration]


                            Leaflet No. 358

                    U.S. DEPARTMENT OF AGRICULTURE




Powder-Post Beetles in Buildings




WHAT TO DO ABOUT THEM


Powder-post beetles cause extensive damage to wood in the structure of
buildings and to wood products used in homes.

The larvae, or grubs, feed on the starch or the cellulose in wood. As
they feed, they bore irregular tunnels through the wood. Borings left
in the tunnels have the consistency of powder.

Powder-post beetles can be controlled by applying an insecticide to the
infested wood. How it is applied depends on the kind of beetle to be
controlled and on the extent and location of the infestation. In some
circumstances a spray will suffice; in others, fumigation is necessary.

  +--------------------------------------------------------------+
  |                                                              |
  |     COMMON AND SCIENTIFIC NAMES OF INSECTS DISCUSSED         |
  |                                                              |
  |    Southern lyctus beetle        _Lyctus planicollis_        |
  |    Common furniture beetle       _Anobium punctatum_         |
  |    Death-watch beetle            _Xestobium rufovillosum_    |
  |    Old house borer               _Hylotrupes bajulus_        |
  |    Red-shouldered shothole borer _Xylobiops basilaris_       |
  |    Black-horned pine borer       _Callidium antennatum_      |
  |    Bamboo powder-post beetle     _Dinoderus minutus_         |
  |    Bamboo borer                  _Chlorophorus annularis_    |
  |                                                              |
  +--------------------------------------------------------------+




KINDS


Powder-post beetles are divided into five groups--lyctus beetles,
anobiid beetles, bostrichid beetles, cerambycid beetles, and cossonid
weevils.

Lyctus beetles are reddish to blackish, about 1/4 inch long, and
slightly flattened. One common species is known as the southern lyctus
beetle.

Anobiid beetles are similar to lyctus beetles in color and size, but
are cylindrical. The common furniture beetle and the death-watch beetle
belong in this group.

Bostrichid beetles are reddish, brown, or black; they are 1/8 to 3/4
inch long, and cylindrical.

The heads of anobiids and bostrichids are directed downward and are
covered by a "hood."

The cerambycids, also known as roundheaded or long-horned beetles,
are blue, black, or pale yellow to reddish brown, and often bear
distinctive markings on the head or the wing covers. They are 1/2 to
1 inch long, and vary in shape. The old house borer belongs in this
group. It is black, and has grayish markings on the wing covers. It is
about 3/4 inch long.

Cossonid weevils are reddish brown or black, 1/8 to 1/5 inch long, and
oval to cylindrical. Their heads are drawn out to form a short, broad
beak. Cossonids are the only weevils that infest wood; other weevils
infest grain or growing crops.




LIFE CYCLE


The adult females lay eggs on or in wood. The eggs hatch into larvae,
which develop as they tunnel the wood. The tunneling continues
throughout the larval stage, which lasts for months or years, depending
on the kind of beetle.

The full-grown larvae transform to pupae, which become adult beetles.

The adults of many kinds of powder-post beetles bore circular holes to
the surface of the wood and emerge; others make oval holes. Some emerge
in early spring; others, including the old house borer, emerge in early
summer. Mating and egg laying follow.

The life cycle of lyctus beetles varies from 3 months to 1 year,
depending on the species and on regional differences in temperature,
moisture, and availability of wood of high food value.

The life cycle of anobiid beetles is sometimes completed in about 1
year and sometimes in 2 years.

Most of the bostrichids and cerambycids complete the cycle in about
1 year, but a few of the latter require several years. The old house
borer, a cerambycid, requires 5 to 7 years in the North, and less time
in the South. In all but a few months of its life cycle, it is in the
larval stage. Larvae 3 or 4 years old are often found in the woodwork
of buildings only 1 or 2 years old--evidence that stored lumber is a
source of infestation.

Cossonid weevils complete the cycle in about 1 year.




EGG LAYING


The females lay eggs on or in wood that satisfies their egg-laying
requirements and the food requirements of the larvae. These
requirements differ among the species. Hence different kinds of wood
are infested by different species of beetles.

Lyctus beetles infest hardwoods. Cossonid weevils infest softwoods.
Some anobiids, bostrichids, and cerambycids infest hardwoods, and some
infest softwoods.

For some species bark is an egg-laying requirement; for others it is
not.

Some anobiids infest moist wood containing decay organisms, which
appear to aid development of the larvae.

[Illustration: Adult of the southern lyctus beetle.]

[Illustration: Adult of the old house borer.]

[Illustration: Adult of the red-shouldered shothole borer, a bostrichid
beetle.]

_Cover:_ Adult of an anobiid beetle, _Xyletinus peltatus_, and pine
sill damaged by larvae of this beetle.

The porosity of the wood, the moisture content, the starch or cellulose
content--these also relate to egg laying.

The adults of some species remain on the wood from which they emerge,
and reinfest it. Others crawl or fly to similar wood and attack it.

A beetle may lay only a few eggs or as many as 60 or 70; the number
depends on the species of beetle and on the condition of the wood.


=Infestations in Hardwoods=

Seasoned hardwoods.--Beetles that infest seasoned hardwoods
lay eggs on or in the wood from which they emerge. Hence the same wood
may be infested repeatedly. These beetles do not require bark for egg
laying.

[Illustration: Oak board damaged by larvae of the southern lyctus
beetle.]

Lyctus beetles lay eggs in exposed pores in the sapwood of oak, ash,
hickory, walnut, pecan, gum, persimmon, maple, cherry, and a few other
hardwood species. The larvae are found in hardwood flooring, furniture,
picture frames, and trim.

Anobiid and cerambycid beetles lay eggs in crevices on the surface of
the wood; cerambycids also lay eggs in emergence holes.

Bostrichid beetles that bore into seasoned hardwoods often bore
chambers at the sides of their tunnels and lay eggs in them.

Unseasoned hardwoods.--Bostrichids that infest green and
seasoning hardwoods lay eggs in pores leading from the entrance
tunnels. The red-shouldered shothole borer is one of these. Bostrichids
frequently attack bark-covered wood. They usually do not reinfest the
wood from which they emerge.


=Infestations in Softwoods=

Seasoned softwoods.--Some kinds of beetles infest seasoned
softwood lumber used in the structure of buildings.

Certain of the bostrichids require bark for egg laying. They infest
lumber that has bark on the edges. Such lumber is often used in
framing, subflooring, and roofing. The females lay eggs in the bark.
The larvae of some species complete their development in it; others go
to the adjacent wood to do so. The adult females may reinfest the wood
from which they emerge.

Other beetles that infest seasoned softwoods do not require bark
for egg laying. Among them are the old house borer and the cossonid
weevils. The females lay eggs in crevices in the wood. They may infest
the same wood repeatedly.

The old house borer infests framing and subflooring. It is found in old
and new construction and in stored lumber. Cossonid weevils are found
in pine flooring, baseboards, wall stops, and roof trusses.

Unseasoned softwoods.--The beetles that infest green and
seasoning softwoods include several cerambycids--for example, the
black-horned pine borer--and a few bostrichids. Most of these beetles
require bark for egg laying. The adult females usually do not reinfest
the wood from which they emerge; they seek other unseasoned wood and
lay eggs in the bark.

[Illustration: Larva of the old house borer. Enlarged about 5×.]


=Infestations in Bamboo=

Certain species of bostrichid, cerambycid, and lyctus beetles infest
bamboo products such as furniture. Venetian blinds, draw drapes,
baskets, fans, and fishing poles.

Plant-quarantine inspectors at United States ports of entry often
intercept the beetles in bamboo products imported from the Far East.
Among the beetles intercepted are the bamboo powder-post beetle, a
bostrichid, and the bamboo borer, a cerambycid. These beetles and the
lyctus beetles may reinfest the material from which they emerge.

[Illustration: Pine floor joist damaged by larvae of the old house
borer]




DAMAGE


The increase in building activity that followed World War II brought
the destructiveness of powder-post beetles to widespread attention. The
more buildings, the more damage.

The old house borer is rapidly spreading over the eastern half of
the United States, and is found more and more in lumber used in new
construction. It is becoming one of the most serious pests of wood in
buildings.

Powder-post beetles damage wood by tunneling and by cutting surface
holes.

Tunneling is done by the larvae of all kinds of powder-post beetles,
and by adult bostrichids and cossonid weevils. The larvae of anobiid
beetles leave elongate pellets of excreted wood in their tunnels.
Other larvae leave powderlike borings. Severely damaged wood becomes a
crumbly mass of pellets or of borings, and sometimes has a honeycombed
appearance.

Since the insects do most of their tunneling in sapwood, structural
damage is rare in large timbers.

Surface holes mar the appearance of wood. Those most commonly seen are
made by adult beetles when they emerge from the wood. Those made by
many of the smaller beetles are about 1/8 inch in diameter. They give
wood the appearance of having been hit by buckshot, and are called
shotholes. Larger beetles make holes 1/4 to 3/8 inch in diameter.

Emergence holes made by the old house borer are oval. The lengthwise
measurement is about 1/4 inch.

The larvae of some species, including the lyctus beetles, make holes to
the surface of the wood and expel borings through them. The larvae of
the old house borer seldom pierce the surface; they pack their borings
behind them.




DETECTION


Aside from observing tunneled wood, there are several ways of detecting
powder-post beetle damage.

You may see surface holes, or borings that have been ejected from them.
The borings may be in piles near the holes or, where timbers overhead
are attacked, they may be on the floor below.

You may see adult beetles crawling on the wood.

In quiet surroundings you may hear a rasping or ticking sound that is
made by tunneling larvae. This is the best way to detect larvae of the
old house borer. Their ticking is sometimes audible several feet from
where they are working. By determining the source of the sound and
by probing the wood with a sharp tool, you can locate the tunnels. A
further aid is to look for blistered wood.

Sometimes the larvae of cerambycid beetles can be heard working beneath
bark on green or partially seasoned wood. They frequently are found in
firewood. They resemble the old house borer, but they have different
habits and do not infest seasoned wood. When the adults emerge,
they seek more green wood to attack. If they cannot escape from the
building, they die in a few days.




WHAT TO DO


Consider whether the control problem is one that you can handle
yourself or whether it is one that requires the services of a
pest-control operator.

If you have a severe infestation, or one that is behind paneled or
plastered walls, or in some other hard-to-reach place, it may be that
only an experienced pest-control operator with the proper equipment can
do a satisfactory job.

If the infestation is light and easy to reach, you may be able to
handle the control job yourself. Spraying or brush-coating the wood
with an insecticide may suffice.

If wood has been so badly damaged that its structural strength is
impaired, it should be replaced. Coordinate the repair work with the
control work.


=Spraying or Brushing=

Beetles that make numerous small holes in the surface of wood are
controlled by saturating the wood with a deodorized kerosene, such as
deobase or ultrasene, which contains either 5 percent DDT, 2 percent
chlordane, 0.5 percent dieldrin, or 0.5 percent lindane.

With 1 gallon of any of these materials you can treat at least 100
square feet of wood surface. Use no more of the material in a single
application than is needed to wet the surface. Repeat the application
until the wood is saturated. Apply with a garden sprayer or a
paintbrush.

The treatment is also effective against infestations in furniture and
other wood products.

For best results in treating any kind of material, first remove the
finish. This is especially desirable when you treat a large area, such
as a floor, but it may not be desirable when you treat ornamental
products. Where an infestation in a floor is so small that removal of
the finish is undesirable, go ahead and treat the floor, but do not
walk on it until it has dried. The drying takes several hours.

The old house borer and other beetles that do not make entrance
holes in the surface of the wood can also be controlled by surface
applications of these chemicals. Larger quantities must be used,
however, especially where thicker wood is concerned, such as floor
joists, studs, and roof rafters. For such materials, at least 1.5
pints of the insecticide per cubic foot of wood is needed to reach the
beetle larvae. This is equivalent to treating the exposed surfaces of 7
linear feet of a 2- by 10-inch floor joist, 12 feet of a 2- by 6-inch
roof rafter, 18 feet of 2- by 4-inch studding, or 12 square feet of
subflooring. Even with this thorough treatment, it may take from 3
weeks to 3 months before all the larvae are reached and killed.

The homeowner can best apply such a quantity of insecticide by using
a sprayer or a pint-size plastic wash bottle of the squeeze type,
equipped with a tube that will produce a pinpoint stream. This makes it
possible to apply small enough quantities to cover the surface without
causing the liquid to run off. Repeated applications at different
times are necessary for complete absorption by the wood and effective
penetration. A pest-control operator can obtain results quickly by
injecting the chemical under pressure through boreholes spaced at short
intervals in the infested wood.


=Slow-Diffusion Method=

Where pressure equipment is not available and you want to use the
bore-hole or slow-diffusion method on isolated infestations in wood
that is readily accessible, you can use the following procedure:

1. Bore a downslanting hole about 1/2 inch in diameter and 1 inch deep
into the wood near the place where a larva is working.

2. Insert a tight-fitting metal or glass tube in the hole. Let about
1/4 inch of the tube project.

3. Place one end of a rubber tube over the projecting portion of the
metal or glass tube, and connect the other end with a funnel. The
funnel should be supported so that it will stay in place until the
treatment has been completed.

4. Pour insecticide into the funnel. Use any of the preparations
mentioned in the discussion of spraying and brushing. Leave the
equipment in place about 48 hours, or until the insecticide is taken
up. The insecticide flows into the infested wood, is absorbed for a
distance of several inches around the hole, and reaches and kills the
larva.

If several larvae are working in places as much as 18 inches apart,
individual treatment is needed.


=Fumigation=

Treatment of a heavy infestation of powder-post beetles by spraying
or brushing or by the slow-diffusion method is impractical where the
wood is hard to reach; particularly when it is located behind plastered
walls or covered by paneling or insulation.

Such an infestation can be controlled by fumigation--_but this work
must be done by a licensed fumigator_.

Hydrocyanic acid gas or methyl bromide gas is used in fumigating. Each
is very poisonous, and heavy dosages have to be used.

After fumigation, the building must be aired to make it safe for
reoccupancy. The fumigating and the airing require 2 to 4 days.

Fumigation methods of the "home-remedy" type--such as burning sulfur
candles--are ineffective because the fumigant does not penetrate the
infested wood.




PRECAUTIONS


The insecticides mentioned in this leaflet are poisonous to people and
to animals. Keep them where children and pets cannot reach them. Do not
let them come in contact with the body. When applying them, wear rubber
gloves, a cellulose acetate type of face-guard, and a rubber or leather
apron. When spraying an overhead area, do not stand directly under it.

Guarding against explosions.--Apply a coarse spray. It is
effective and safe to use. A concentrated fine mist is ineffective and
may explode in the presence of a spark or flame. Do not smoke while
spraying. Shut off pilot lights.

Pressure.--In spraying, use only enough pressure to wet the
surface of the wood. Too much pressure may cause spray to splash onto
the body. If you apply the insecticide in an enclosed place, make sure
that the air can circulate freely. Keep doors and windows open; if
necessary, use a fan. The purpose is to prevent odors from accumulating
in the building.

If you treat a floor that has a finished ceiling under it--for example,
the floor of a second-story room--avoid applying too much material. If
you do, it may run through to the ceiling and cause a stain. Removal of
the floor finish before applying the insecticide makes it unnecessary
to apply a large amount; the wood absorbs most of it.

If you apply the oil solution to parquet flooring, do it very lightly.
If you apply too much, the oil may dissolve the asphalt in which the
flooring is set. The dissolved asphalt may stain the floor. Around the
edges of the floor, it may "creep up" and damage the walls.

If you have applied insecticide with a garden sprayer, rinse out the
tank and hose before putting the sprayer away. This prevents the
gaskets from shriveling and keeps oil from getting on plants the next
time the sprayer is used in the garden.

Food cabinets.--In treating a food cabinet, do not use an
insecticide because it might contaminate food. Use deodorized kerosene
alone. It has little odor and evaporates quickly. Take the cabinet
outdoors to treat it, and leave it there until the kerosene odor
disappears.

Fumigation.--The fact that fumigation work must be done by a
licensed operator is stated on page 7.

Only isolated buildings can be safely fumigated. If an apartment, a
row house, or part of a duplex were fumigated, the gas might penetrate
walls and kill persons in an adjoining unit.

Methyl bromide gas is odorless, but in the presence of articles having
a high sulfur content, or containing animal matter, sponge rubber, or
iodized salt, a chemical change takes place and a garliclike odor is
apt to be given off later. Before this gas is used, see whether such
articles are in the building; if they are, remove them. This need not
be done if hydrocyanic acid gas is used. However, hydrocyanic acid gas
tarnishes silver and spoils unexposed photographic film; before it is
used, remove silver and film.



     Prepared by R. A. St. George and T. McIntyre, entomologists,

          Division of Forest insect Research, Forest Service

               Washington, D.C. · Revised November 1959


                 U.S. GOVERNMENT PRINTING OFFICE: 1959



     For sale by the Superintendent of Documents, U.S. Government
          Printing Office Washington 25, D.C. - Price 5 cents




Transcriber Note


Illustrations moved to prevent splitting paragraphs.