Control of the black turpentine beetle / by Edward P. Merkel

GEORGIA FOREST RESEARCH PAPER
v. .

15
January, 1981

CONTROL OF THE BLACK TURPENTINE BEETLE

BY EDWARD P. MERKEL
RESEARCH DIVISION

Received
FB 8 1982
DOCUMENTS UGA LIBRARIES

GEORGIA FORESTRY COMMISSION

AUTHOR
Edward P. Merkel is a Forest Entomology Consultant from Lake City, Florida. He received a B.S. degree from the State
University of New York College of En-
vironmental Science and Forestry. Mr. Merkel is retired from the U.S. Forest Service having served as a Research Project Leader with the Southeastern Forest Experiment Station, Olustee, Florida, for 20 years.
ACKNOWLEDGMENTS
The author thanks the U.S.D.A., Forest Service, Southeastern Forest Experiment Station and the Georgia Forestry Commission for the use of the photographs in this
publication.
PHOTOS ON THE COVER
Background Photo - Slash pines killed by the black turpentine beetle. Left Photo - Adult black turpentine beetle. Right Photo - Large pitch tubes on the bark at the base of a pine tree attacked heavi-
ly by the black turpentine beetle.

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BY
EDWARD P. MERKEL

THE BLACK TURPENTINE BEETLE
The black turpentine beetle, Dendroc-
tonus terebrans (Olivier), is a black, hardshelled beetle about 3/8 inch long with
head- and tail ends rounded (Fig. 1). The
black turpentine beetle (abbreviated
"BTB") is one of the largest members of a group of insects known as bark beetles. Bark beetles are so named because they tunnel between the bark and wood of
trees, thereby introducing blue stain fungi, disrupting water movement, and causing eventual death of the tree.
All pine species in Georgia are subject to attack by BTB. The beetle has been particularly destructive to slash and long-
leaf pine worked for gum naval stores in
the Coastal Plain Region. During the early 1950's, before insecticidal control methods had been developed, a severe wide-
spread outbreak of BTB virtually forced many turpentine farmers out of business.
WHERE BLACK TURPENTINE
BEETLES ATTACK
BTB attacks freshly-cut pine stumps
and trees stressed or weakened by disease, fire, lightning, drought, growth stagnation,

or old age. Man also creates conditions in forest stands that invite BTB attacks. For
example, "skinned" tree trunks or large roots and soil compaction incurred during
logging. In urban areas BTB is commonly a pest at construction sites when trees are
damaged during digging and grading oper-
ations.
Pine stands worked for naval stores are periodically subject to BTB attacks, particularly during droughts, or when narrow bark bars between faces increase tree stress. Trees wounded mechanically and
treated with the herbicide, paraquat, for
lightwood production may also be attacked by BTB and other bark beetles.
HOW TO RECOGNIZE BLACK
TURPENTINE BEETLE ATTACKS
Before appropriate control procedures can be started, one must determine wheth-
er BTB or other bark beetles are attacking
the pines. The best clues for identifying
the presence of BTB are the large pitch
tubes (Fig. 2) that are found within the lowest three to six feet of the tree trunk. Pitch tubes resulting from the earliest attacks, however, usually occur within 18 inches above the ground. The pinkishwhite to reddish-brown pitch tubes have a diameter about the size of a 50-cent piece and form on the bark surface at the point where the beetles bore through the cuter bark into the pitchy white inner bark next to the wood.

Figure 2. -Typical pitch tubes made by black turpentine beetles when
attacking the lower trunks of southern pines.

EGG

LARVA

PUPA

ADULT

Figure 1. -Life, or developmental, stages of the black turpentine beetle.

- LEGEND -
(1) Pitch tube at beetles' entrance into bark.
(2) Female BTB excavating egg gallery between bark and wood. (3) Male BTB clearing egg gallery of pitch and debris.
(4) Elongated pocket containing eggs along side of gallery. (5) Irregular-shaped area of inner bark consumed by groups of larvae (grubs).
(6) BTB pupae (transformation stage from grubs to beetles).
(7) Newly-formed (pale yellow or callow) beetle. (8) Callow adults turn to black color before emergence from tree or stump. (9) Emergence (exit) hole of newly-formed beetles.
apwewcEU
Figure 3. --Development of the black turpentine beetle in the inner bark of southern
pines.

During construction of the egg gallery in the inner bark (Fig. 3), the attacking beetles must work to keep from being overwhelmed by the flow of gum; so this
gum is continually pushed out of the
entrance hole forming the pitch tube. Pitch tubes resulting from successful
BTB attacks are reddish brown in color
and have a coarse granular texture due to the mixture of pitch and dark-colored bark particles; after a month or two the pitch tubes have a grayish color. Pitch tubes formed during unsuccessful beetle attacks are called "pitch-outs" and are characterized by their pinkish-white to yellow color and their composition of mostly pitch mixed with few bark particles giving them a smoother texture.
Pines attacked by BTB are also commonly attacked by other bark beetles
such as the southern pine beetle and pine engraver beetles. Pitch tubes made by these other bark beetles occur higher on
the trunk and are usually much smaller than BTB pitch tubes, i.e., diameter of a dime or smaller. Fine-textured, reddishbrown bark particles, called boring dust, are often produced when other bark
beetles attack and can accumulate in noticeable amounts around the base of the tree, in bark crevices, and in naval stores cups and gutters.
Fluffy, yellowish-white piles of finely-
shredded wood particles usually appear at the base of trees attacked by BTB and
other bark beetles. These piles are produced by the ambrosia beetle, Platypus flavicornis (F.) which bore directly into
the wood at the base of the tree. Ambro-
sia beetles do not kill the pines, but
usually attack after successful bark beetle
attacks when the tree's foliage has begun to fade. When ambrosia beetle boring dust encompasses at least half the circum-
ference of the tree's base, the tree almost
invariably dies.
More positive identification of the
BTB can be made by peeling back the bark down to the wood surface with a
hatchet to expose the insect feeding galleries. The first hatchet cut should be made just above a pitch tube and then the bark should be steadily pried from the
wood working downward for about 12
inches; if no galleries or insects are found after the first piece of bark is removed, remove sections of bark from either side of the first piece removed. The beetles or their immature stages, i.e., eggs, larvae pupae (Figs. 1 and 3), will usually be found on the inner surface of the remov-
ed bark section or on the exposed wood
surface. Assistance in identifying bark beetles can be obtained at an office of the
Georgia Forestry Commission or County Agricultural Extension Agent.

HOW BLACK TURPENTINE
BEETLES PRODUCE
NEW BROODS
As in the case of all bark beetles, the
BTB passes through an egg, larval or grub,
and pupal stage (Fig. 1) in the inner bark before transforming into a beetle (Fig. 1). The newly-formed beetles emerge from stumps and infested trees that have died and attack additional fresh-cut stumps and green trees to start the life cycle over
again. The life history of the BTB is
illustrated in Fig. 3 and differs from other
pine-infesting bark beetles in the following ways: (1) clusters of eggs are laid in
one or more narrow elongated pockets, usually on one side of the egg gallery (Fig. 3-(4)); and (2) groups of larvae feed side by side excavating a large continuous area or cave-like gallery which increases in size as the larvae grow and move away from the egg pocket: sometimes an area of one to two square feet of inner bark is consumed by the larvae.
The black turpentine beetle takes three to four months to complete a single generation, that is, from the time the parent beetles enter a tree or stump until the newly-formed beetles emerge. In contrast, other southern bark beetles complete a single generation in twenty to forty days. In the warmer climate of south Georgia
the BTB may complete two and one-half
to three complete generations per year
and adult activity slows down only during the colder months (November through
February).
Fig. 3 is a graphic presentation of the development of a single generation of the
BTB from the time that the attacking
parent beetles enter the bark until the new-generation beetles mature and emerge
from an infested tree or stump. One rarely finds all life stages of the BTB
under the bark at any given time; but beetle development follows the numerical sequence as shown in figure 3. For example, the large pitch tube (Fig. 3 - (1)) is formed at the hole where female (Fig. 3 - (2)) and male (Fig. 3 - (3)) parent beetles enter the bark and begin egg gallery construction. It should be noted that larvae or grubs, (Fig. 3-(5)) after hatching from the eggs (Fig. 3-(4)), shed their body covering ("skins") several times
increasing in size after each molt. When
larvae mature they leave their group feeding sites along the edge of the irregularshaped gallery and back-track into the previously-consumed area of inner bark containing dry, fine, granular boring material and form eliptical-shaped cells in which to pupate (transform to beetles)

(Fig. 3 - (6) and (7)). One or more new adults (Fig. 3 - (8)) may emerge through a
single exit hole (Fig. 3 - (9)). Attacking beetles after depositing one
or more egg clusters may emerge through
the bark and attack elsewhere on the same tree or attack other trees. Also, at-
tacking beetles may be repelled by large flows of pitch and may attack elsewhere on the same tree or attack other trees. Numerous pitch tubes on a tree do not always mean successful attack and tree death (See "How To Recognize BTB
Attacks").
ATTACK BEHAVIOR OF THE
BLACK TURPENTINE BEETLE

Although beetle attacks (pitch tubes)

commonly occur to a height of six feet

above ground, the majority are found

within the basal three feet of attacked

trees, k is important to note that the first

attacks usually occur within the basal 18

inches of tine tree and subsequent attacks

increase in height on the tree trunk as in-

festation progresses. BTB attacks on in-

dividual trees may last for four to seven

months .

It has been observed that as the

number of pitch tubes increases above

ground, additional attacks occur beneath

the soil surface on tap and large lateral

roots larger than one inch in diameter.

Successful BTB brood development in

roots has only been observed within the

upper 18 inches of soil. It is not known

whether first attacks on a tree occur on

the roots; but it is not unusual to find

early attacks in the root-collar area be-

neath the needle litter.

INSECTICIDAL CONTROL OF THE BLACK
TURPENTINE BEETLE

There are two courses of action which can be followed if trees are attacked by BTB: (1) Salvage all infested trees and spray stumps with an insecticide registered for control of BTB; or (2) when sal-

vage is impractical, spray all attacked trees up to the height of the highest pitch

tube with a registered insecticide. Spray-

ing should continue as long as additional

trees continue to be attacked '\n_ the stand.

Bjv

so

doing ,

many

attacked

trees

will

be

saved ,

additional

attacks will

be prevent-

ed jDn_ trees already under attack , and

subsequent

beetle

activity

reduced .

Don't

be fooled by only a few pitch tubes at the

base of the tree ! BTB works long and

persistently and will eventually kill the

tree ; so act promptly _rf_ you want to save

trees !

Preventive spraying, i.e., the applica-
tion of an insecticide before BTB attacks
the tree, is expensive but effective where the timberland owner wants to protect high-value trees. Preventive spraying can

be used in areas cut back to seed trees, in seed orchards, and on street and yard trees. Water emulsions of insecticides should be used instead of oil solutions in situations where lawns and ornamental shrubs might be damaged by the fuel oil.

MIXING AND APPLYING
INSECTICIDES

Black turpentine beetle attacks are not
always fatal to the tree, but when they
are, the green color of the healthy foliage fades from yellow-green to pale yellow and finally to a brick red. Fading of
foliage may begin four to eight months
after the initial attacks. In contrast, southern pines attacked by other bark beetles usually begin to fade within three
to four weeks after initial attack. Black turpentine beetle infestations
are difficult to detect from the ground or air because of the long attack period and the long, but highly variable, time interval between initial attacks and foliage fading.
Stands infested by BTB generally contain
trees in all stages of attack, foliage dis-
coloration, and crown deterioration. The groups of faded trees so characteristic of
other bark beetle infestations will not be
seen. One is more likely to find a majority of green trees under attack with dead and dying trees scattered sporadically throughout the stand.

Before purchasing an insecticide check

with your local County Agricultural Ex-

tension Agent or State Forestry Commis-

sion office to determine what insecticides

are registered currently for BTB control. When this publication was prepared, only

two insecticides, lindane and chlorpyrifos,

were registered for BTB control.

After

the

insecticide [s

purchased ,

read

the label on the container carefully for

dilution ,

mixing ,

and

application

instruc -

tions . Other recommendations on the

label ,

concerning

the

use of special

safety ,

equipment ,

should

be

followed

closely !

Insecticides for bark beetle control are

usually sold as water emulsifiable or oil

soluble concentrates. The water emulsifi-

able concentrates are diluted with water

and the oil soluble concentrates are dilut-

ed with No. 2 fuel oil.

The insecticide, lindane, can be used
for BTB prevention or control as a 0.5%

concentration in either water or No. 2

fuel oil; whereas the insecticide, chlor-

pyrifos, is used at a 1% concentration in water only. The Appendix will show you how to properly dilute any insecticide
concentrate.
For remedial control, that is when you want to kill beetles after they have enter-
ed the tree, oil solutions will give better bark penetration and a longer residual effectiveness than water emulsions in pre-
venting additional BTB attacks on the
same tree. If large numbers of trees or stumps require spraying, it would be much less expensive to use a water emulsion. Water emulsions are also preferable for use in urban areas and near dwellings where oil solutions may damage lawns, flowers and shrubs.
Spraying is easily accomplished with an ordinary, hand-pump, compressed air sprayer of one to three gallon capacity. Use a spray nozzle that will give a fanshaped or cone-shaped spray pattern of
coarse droplet size. When a fine mist is used to spray, too much time is required and it is more difficult to achieve penetration of deep bark crevices. A nozzle
that produces a solid stream will give good bark coverage but normally there is waste of spray material because of exces-
sive run-off.
On infested trees begin spraying about
a foot above the highest pitch tube on
the tree trunk. On uninfested trees, where prevention of BTB attacks is desired, be-
gin spraying the trunk at waist-height. Spray one side of the tree first, starting at the highest point on the trunk, moving the nozzle back and forth horizontally, and gradually working toward the tree base. Sufficient spray material should be applied so that it forms small rivulets that
run into the bark crevices. Then move around the tree, again starting at the highest point on the trunk, and proceed as just described making sure your spray
overlaps slightly the portion of the trunk
sprayed previously. Do this until the en-
tire bark circumference has been covered
thoroughly. Finally make one pass around
the entire base of the tree, directing the spray at the root collar, that is, the junc-
tion between the tree and the soil. On ma-
ture trees, particularly on low, poorlydrained sites, there is often a thick accumulation of loose bark scales and needle litter at the base of the trees. Better spray coverage of the root collar will be obtained if the litter is scuffed away from the base of the tree.
INSECTICIDAL CONTROL IN
NAVAL STORES OPERATIONS

time-consuming if the following procedures are followed:
1. Chippers should learn to recognize
BTB attacks; and since they visit all
worked trees throughout the chipping season, they can scout for and
report locations of BTB attacks when they first appear. Provide
each chipper with a roll of brightlycolored plastic flagging tape to be tied around the tree trunk at breast height, or at eye level on a nearby
bush, when BTB pitch tubes are encountered. BEWARE! - some of
the first pitch tubes are hidden from view under or behind the turpentine cup and in deep bark crevices near the ground line.
2. Spray attacked trees as soon as possible after the chipper flags them. Spraying trees promptly prevents
additional BTB attacks on the same trees. When BTB populations are
high, other trees, in addition to
those sprayed initially, may become attacked throughout the summer
and fall. Therefore, keep up with the newly-attacked trees and spray them each month if necessary.

Don't allow the number of infested trees to accumulate to the point where you must contend with a
large, costly, spray job.
INSECTICIDAL CONTROL IN
THINNED AND HARVESTED STANDS
Even though BTB breed in freshly-cut
stumps, it is not necessary to routinely spray stumps with an insecticide as a preventive measure. Spraying numerous stumps is costly. Furthermore, there is no
certainty that BTB will breed in the green
stumps and spread to residual trees. Instead, periodically examine the residual stand for about six months after logging
to determine whether the BTB is aggres-
sively attacking trees, particularly trees
damaged by logging. Spray attacked trees
as soon as BTB activity is observed. If a
sharp increase in attacked trees occurs,
all attacked and unattacked damaged trees should be sprayed to the height of the
highest pitch tube or to the height of
logging damage on the trunk such as "skinned" bark.

APPENDIX

The following is a hypothetical label for a concentrated water emulsifiable insecticide showing the chemical ingredients:

INSECTICIDE BRAND X
Active Ingredients
Name of Insecticide
Aromatic Petroleum Derivative Solvent
Inert Ingredients
*Contains 1.65 pounds of active insecticidal ingredient

By Wt.
20% 59% 21%

*AII pesticide labels must contain a statement about the weight (pounds) of active insecticide per gallon of concentrate. With this information, and the following formu-
la, one can readily calculate how much concentrate is required to mix with the desired amount of water, or No. 2 fuel oil, to obtain the percent spray solution needed.

Formula = (gals, of spray wanted) x (% active ingredient wanted) x 8.3 (lbs. of active ingredient per gal. of concentrate) x ( 1 00)
= gals, of emulsifiable concentrate needed

Example

10 gals, spray wanted) x (1.0% active ingredient wanted) x 8.3
[
*(1 .65 lbs. active ingredient per gal. concentrate) x 100

1.0 x 1 x 8J3 = 83_ = 5 L Qr 2 quarts f "Brand X" concentrate 1.65x100 165

Spraying individual trees is a pro-
cedure well-adapted to gum naval stores
operations and need not be costly and

Note: To prepare the final spray mixture place the 1/2 gallon of concentrate into a mixing container and add sufficient water (9Vi gals.) to make a total of 10 gallons
of water emulsion.

Bit
eiOfl OM^I 2737
GEORGIA
FORESTRY
A. Ray Shirley, Director
John W. Mixon, Chief of Forest Research