ALABAMA
Agricultural Experiment
Station
OF THE
Alabama Polytechnic Institute
AUBURN
THE SOUTHERN PINE BEETLE
AND ITS CONTROL
CIRCULAR NO. 15
February, 1912
BY
W. E. HINDS, Entomologist
J. F. DUGGAR, Director
Opelika, Ala.
Post Publishing Company
1912
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THE SOUTHERN PINE BEET LE
AND ITS CONTROL
INTRODUCTION.-It is a well known fact that pine trees
of various species are dying in increasing numbers in Alabama.
This dying occurs usually in groups of trees and has caused
mnch alarm among owners of timber. In a general way it is
recognized that insects are the cause of the trouble but the
blame is usually placed upon the wrong species of insect.
Quite naturally the larger insect species are more frequently
noticed and charged with being the cause of the trouble.
Closer and more careful observation, however, reveals the
fact that the primary cause of the dying of the pines is the
work of very small beetles which attack the living trees. The
nature of the work of these beetles will be described in a
general way in succeeding paragraphs. As a matter of fact
the larger beetles do not injure vigorous healthy trees but are
attracted to those in a weakened or dying condition.
In this circular we shall make no attempt to cover the work
of all those insects which may cause the death of or develop
in dying pines. Our object is to spread more widely informa-
tion in regard to the species which is usually the first cause
of trouble in this State, in order that immediate steps may
re taken to bring this pest under control and thus prevent an
outbreak of the species which is now increasing and seems
likely to do immense damage to the pine forests of Alabama
during the next few years.
We make no claim for originality in the matter of informa-
ticn given herein except in regard to the illustrations used.
The subject of forest insects is sufficiently large to command
a life time of study. The best authority in the United States
on this subject is Dr. A. D. Hopkins, in charge of Forest
Iisect Investigations, U. S. Bureau of Entomology. Dr.
Hopkins has recently issued Farmers' Bulletin No. 476 en-
titled, The Dying of Pine in the Southern States: Cause, Ex-
tent and Remedy. While this publication may be obtained
free of charge by any applicant, it has seemed advisable to
embody most of the information given therein, in this circular,
in order that it may have more general distribution through
46
the State than could be obtained in any other way. We shall
also include some information drawn from several other publi-
cations issued by Dr. Hopkins upon the bark beetles.
DESTRUCTIVE BARK BEETLES OCCURRING 
IN
ALABAMA.
According to Dr. Hopkins, only one species of bark beetle
having the ability to kill living pines is likely to be found in
this section of the South. This is known commonly as the
southern pine beetle. It seems quite possible that more careful
field investigations in this State may show that still other
really destructive species occur here. It is not necessary, how-
ever, to wait for such investigations. We know that at least
one of these destructive species occurs and the general meas-
ures for control of all such species would doubtless be the
same. These general measures of control should be put into
operation immediately as the extent of the injury and the
difficulty of securing control of these species is increasing
rapidly with each succeeding season.
Past experience has demonstrated that these destructive
bark beetles, when they occur in great abundance, are able to
kill perfectly healthy timber over large areas before they are
brought under control by their natural enemies or by ether
factors. Thus about twenty years age the same species 
that
is now most common in Alabama became very abundant 
in
Virginia and West Virginia and destroyed timber worth many
millions of dollars before the outbreak subsided. The 
area
then affected was equal to about three-fourths of that of Ala-
bama and Georgia combined. Conditions in the South at 
the
present time indicate that a similar outbreak is beginning in
the South Atlantic and Gulf States.
SECONDARY ENEMIES FOLLOWING THE DE-
STRUCTIVE BARK BEETLES.
As soon as the attack of one of the destructive beetles
causes a weakened or dying condition of a tree, such a tree
becomes at once the breeding place of many other species oft
bark beetles and bark and wood boring grubs which cannot
attack healthy trees. These secondary enemies of a tree 
are
47
dependent on the more aggressive destructive bark beetles or
on other factors that may cause a similar weakened or dying
condition of the trees. Some of them render special service
to the destructive beetles by attacking the twigs, the branches,
and the unoccupied bark on the upper and lower portions of
the trunk, and thus aid in bringing about the certain death of
the trees. There are some insects which live in the galleries
with the adult beetles in the relation of guqsts, others as
scavengers, etc., so that it is always important to distinguish
which are the real primary enemies, which are secondary,
which are Leneficial and which are neutral in their relation to
an affected tree.
THE SOUTHERN PINE BEETLE.
(Dendroctonus frontalis Zimm.)
This is a small, cylindrical, brownish to black beetle varying
in length from about 1-10 to 1-6 of an inch. It is shown
natural size in Plate II, Fig. 1. It attacks healthy, injured and
felled trees of all of the pines and spruces growing from
Pennsylvania southward into Florida and westward into east-
ern Texas. The beetles excavate long winding egg galleries
through the inner bark just barely marking but not burrowing
into the surface of the wood. These conditions are shown in
Plate II, Fig. 1, and Plate III, Fig. 2. The female lays her
eggs at frequent intervals along the sides of the egg galleries
and the white legless grubs burrow into the inner bark making
their galleries away from the original burrow of the parent.
The change from the grub to the beetle stage occurs in 
the
outer bark and soon thereafter the mature beetles may emerge
and fly in all directions seeking new healthy trees to attack.
The period of flight in Alabama probably extends from 
the
latter part of March until the time of frost in the fall. 
They
may pass through the winter in various stages of development
so that emergence in the spring is irregular from trees that
were infested the preceding fall. This may occupy a 
period'
of three or four months. By the end of July at the latest all
of the trees attacked during the preceding year will be entirely
dead and abandoned by this species of beetle although 
they
may still serve as breeding places for many of the secondary
species as mentioned above.
' .,A -~ " 
,. ' 
fr . ,, 
_,.
1etl, \ .. Pit I trs bes eau ink tunaIr, ;
49
There may be from three to five generations each season
of the southern pine beetle. These generations overlap so
that it is difficult to distinguish them and to indicate any
definite periods during which the pines are killed. There seems
to be a rather continuous dying throughout the season with
the climax occuring apparently during June, July and August
in this State.
FIRST ATTACK. These beetles evidently fly principally
late in the evening and at night. They are attracted to lights
and are frequently found in great numbers around electric
lights particularly. From the fact that infested trees usually
occur in well defined groups, it seems quite certain that the
beetles emerge and fly in swarms. They are sometimes found
congregated in large numbers under the loose flakes of bark
on healthy trees just before they begin their simultaneous
attack on the trees. It appears frequently that the beetles all
leave the vicinity of the group of trees in which they have
developed and the next indication of their work may be found
in a group of trees at some little distance away. We cannot
say just why this general movement occurs so frequently as
seems to be the case.
As a usual thing the beetles attack first the middle and upper
portions of medium sized trees often appearing to select the
largest and best trees first. This work occurs so far from
the ground that we must depend for recognition of it upon
some of its secondary effects upon the tree.
EVIDENCES OF DESTRUCTIVE BEETLE WORK.
Danger centers are indicated in a general way by the occur-
rence of dead pines which have not been injured by fire or
other destructive agency. This condition is shown in Plate I.
The bark of trees which have been abandoned by broods of
these beetles has the general appearance shown in Plate III,
Fig. 1. The "shot holes" of this species are hardly as large
as the head of a pin. Under this bark the wood shows the
characteristic surface markings and the deep black stain'n"
indicared in Plate III, Fig. 2. Frequently also the bark shows
"pitch tubes" exuding from the beetle burrows as shown in
Plate 11, Fig. 2.
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iat
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4 a
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0
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a 4 .~9 ~ 0
:t
4'
ft
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P.
2 Siiiac LU el of co (' d II I(Ui;L ((4 Icc of C 
utmu and ulu
I a k staining, 
Oui~inaI j
51
The burrows of beetles and grubs extending through the
delicate inner bark cross and recross each other until they
finally completely girdle the tree in many places. The girdling
cuts off the flow of sap from the roots to the top of the tree
and brings about its death within a few weeks after the attack
begins. The leaves or needles of infested trees quickly show
the effect of this vital injury and on all trees except those
attacked late in the fall, the needles begin to fade, turning
yellow first at their bases and gradually becoming dry and
brown throughout. The tops of such trees are known as
"faded tops." By the time the foliage has become reddish
brown, the beetles have usually abandoned the trees and are
attacking others. These abandoned trees may contain some
belated individuals of the destructive species but most of the
insects found in them from this time on are not of primary
economic importance. The trees to be especially sought for
in order to reduce the numbers of this southern pine beetle
are those which show evidences of recent attack and from
which the beetle brood has not yet emerged.
SPREADING OF THE PEST.-These beetles spread upon
the emergence of the adults at the end 
of each generation.
This may occur several times, therefore, 
during the season.
The beetles are quite strong 
flyers and it has been determined
that they may spread to a distance 
of three or four miles from
the locality in which they developed. Each 
patch of dying
trees may be considered as a center 
of infestation which en-
dangers healthy timber around it within 
an area of twenty-five
to thirty square miles. The swarming 
broods may move in
any direction and start another 
center of infestation among
healthy trees. It is evident that 
the occurrence of even a few
such centers a few miles apart 
really endangers all pines
within a large area. The presence 
of these beetles constitutes
a greater danger to pine than 
does the occurrence of the ordi-
nary forest fires. The centers 
of infestation really call for
even more determined treatment 
in order to protect living
timber than would be needed 
in the case of fire. Measures
of control will depend quite 
largely for their fullest success
upon general cooperative 
action over the threatened 
territory.
52
CONDITIONS FAVORING INJURY.-Favorable condi-
tions for the multiplication and spread of the beetle are found
in areas of large, matured timber and where the trees are
frequently struck by lightning, felled or injured by storms,
etc., during the summer months.
It is a generally recognized fact that the cutting of pines dur-
ing the summer months is almost certain to start trouble. Dur-
ing the winter of 1911-1912 heavy winds in various sections of
Alabama have wholly or partly blown down pines in perfectly
healthy groves. It would seem that these weakened trees
unless removed before the end of March may be especially
attractive to bark beetles during the coming summer and
serve as centers of serious infestation.
The odor from the exposed wood, and perhaps from the
wilting foliage of a few trees cut in the midst of a healthy
growth of pine during the summer, serves to attract this
species, apparently from a long distance, and to induce attack
on the surrounding healthy trees. Therefore, an irregular
or sporadic local cutting of timber for fuel or any limited
purposes during the summer months furnishes most favorable
conditions for the concentration of individuals from widely
scattered colonies and broods and thus increase their power
of attacking and killing the surrounding living trees. By this
means their forces are greatly augmented and much of the
surrounding timber is killed. If conditions favorable for the
continued concentration of the beetles prevail from year to
year, an invasion like that of 1891 and 1892 may be started
which may far exceed any forest fire in the history of the
country, both in the extent of area covered and in the number
of trees of commercial value killed.
THE MORE IMPORTANT EVIDENCES OF THE PRES-
ENCE AND WORK OF THE BEETLE.
(1) If in clumps or patches of pine, where there is no plain
evidence of serious injury by fire, the foliage fades to pale
green and changes to yellowish and pale brown, it indicates
that the trees are dying from the attack of the southern pine
beetle, and that the bark on such trees is infested with the
developing broods of minute white grubs and transforming
53
beetles. Therefore such infested trees are a menace to the
living trees.
(2) If the trees have reddish brown and partially fallen
foliage or if all of the foliage has fallen, it indicates that the
broods of beetles have emerged and that such trees are no
longer a menace to the living ones.
(3) If the trees die during the period between the 1st of
March and the 1st of October, they will be abandoned by the
broods of beetles within a few weeks after the foliage begins
to fade.
(4) If the trees begin to die during the period between the
1st of October and the 1st of December the broods of beetles
will remain in the bark until the following March or April.
1OW TO LOCATE THE INFESTED TREES.
The location of trees that are infested by the southern pine
beetle is the first and one of the most important things to do
before definite plans are made for the active work of cutting
the trees. Some of the essential things to remember are as
follows :
(1) The southern pine beetle attacks the upper and middle
portions of the trunks of healthy trees.
(2) A freshly attacked tree may show pitch tubes on the
trunk, reddish boring-dust around the base, or there may be
no external evidence of attack until the leaves begin 
to fade.
(3) By the time the tops are faded and the bark on the
middle and upper trunk is dead the broods of the beetles are
in an advanced stage of development; yet, at the same 
time,
the bark on the lower third of the trunk may 
be living and
show no evidence of attack, or may be attacked by other 
kinds
of insects which are not responsible for the death of trees.
(4) As soon as the bark begins to die on any part of the
trunk it is attacked by numerous other insects, including 
the
adults of the "sawyer" borers which do not attack 
healthy
trees.
(5) By the time the tops have changed from pale green to
greenish brown the broods of the southern 
pine beetle are
nearly all developed to the stage when they enter 
the outer
bark to transform to the adults.
54
(6) By the time the tops have changed to a reddish hue the
brocds have developed and are either emerging or have
emerged.
(7) During the warm months the broods will develop and
emerge from a tree within about 30 to 40 days after it is
attacked.
(8) Trees attacked in November will usually carry the
broods over winter. The foliage of some trees will fade and
reach the reddish stage before spring; other trees attacked in
December or later may not fade until the warm days of Feb-
ruary, March, or April.
Therefore, in estimating the character and extent of an
infestation within any given area, or in locating infested trees
and marking them for utilization or treatment, one has only
to consider those with fading or greenish brown foliage, or the
first stage of the yellowish red tops.
ESSENTIAL DETAILS IN METHODS OF CONTROL.
There are certain essential details in the recommended
methods of combating the southern pine beetle which must be
observed in order to avoid not only serious mistakes but possi-
bly ultimate failure:
(a) The principal clumps or patches of dying trees which
are actually infested by the broods of the destructive beetle,
as indicated by the fading and dying foliage, or otherwise,
should be located and marked during the months of Novem-
ber, December, January, and February. In order to do this
work, proper experience or special instruction is required.
Therefore, some one who has had instructions should have
charge of the work in each important area in which control
work is to be undertaken.
(b) The broods of the beetle in the bark of the main trunks
of the medium to larger sized dying infested trees within an
area of 8 or 10 square miles or more must be destroyed in
order to stop their depredations.
(c) The broods may be destroyed by one or more of the
following methods, the work to be done between the 1st of
November and the 1st of March: (Plate IV.)
4( r, p y
n3
April Idt.
56
(1) Removing and burning the infested bark from the
trunks of the standing 
trees; or
(2) Removing and burning the infested bark from the
trunks of the trees after they have been cut down; or
(3) Scorching the infested bark, or burning the wood with
the bark after the trees are cut down; or
(4) Placing the infested portions of the trunks in water; or
(5) Converting the trunks 
of the infested trees into cord-
wood and using the wood for fuel before the beetles leave the
bark; or
(6) Converting the infested trees into lumber or other pro-
ducts and burning the slabs or bark.
(d) It is not necessary to burn the tops or branches of
treated trees or to cut and burn small infested saplings if the
larger infested trees are disposed of.
(e) It is not necessary to remove or destroy the bark on
the lower portion of the trunks or on the stumps if it is not
infested with the destructive beetle, and it is not necessary to
cut or treat dead trees from which the beetles have emerged.
(f) It is necessary and essential that the broods of the
destructive beetle in the bark of any.portion of the main trunks
of the medium to larger sized dying infested trees of any given
locality should be destroyed.
(g) If the wood of the infested trees can be utilized for
fuel, lumber, or other purposes, its value should cover the cost
of the work. If the work of felling and barking the trees is
done at direct expense, the cost will average 10 to 30 cents
per tree.
(h) The cost of protecting the living timber of any locality
with average infestation should not exceed an average of from
1 to 5 cents per acre for the total area of pine-covered land,
and if estimated on a basis of volume it should not cost over
2 cents per cord of the living timber protected.
(i) The best time to conduct control operations against the
southern pine beetle is during the period between November 1
and March 1.
(j) If a pine tree standing among or near a grove or
woods of living pine is either struck by lightning or felled and
barked or split into cordwood during the summer and early
57
fall, it will, as a rule, attract the beetles within a radius of 3
or 4 miles and result in the starting of a new center of infesta-
tion and in the death of a large number of trees.
(k) The principal owners of pine in each community should
cooperate in the disposal of the required infestation but should
not undertake the work until some one or more of the owners
is sufficiently familiar with the essential details of the proper
mnethods.
REQUIREMENTS FOR SUCCESS.
The requirements for success in any effort to protect the
living pine from the destructive attacks of the southern pine
beetle are the destruction of the broods of the beetle in the
bark of the main trunk of the dying infested trees before they
leave the bark. This is accomplished by the adoption of one
or more different methods of direct utilization of the infested
trunk, or treatment at direct expense in cases where the wood
can not be utilized.
The attainment of the best success from the practical appli-
cation of any of these methods will depend on their adaptation
to local conditions and requirements for disposing of the
infested timber and strict adherence to certain details which
are absolutely necessary to the destruction of the broods.
The period in which to locate and mark the trees that are
actually infested and in which the marked trees should be
utilized or treated to kill the broods is between the 1st of
November and the 1st of the following March, but in some
cases the period may be extended to the 1st of May.
The adoption of the method of destroying the broods which
in each case is the most economical and effectual can be de-
termined by the owners in each community if they are 
suffici-
ently informed on the essential facts.
Detailed advice, recommendations, or conclusions as to the
most economical and effective method of procedure for 
any
given area should be deferred until certain reliable informa-
tion is at hand in regard to the local condition as to (a) the
character and extent of the infestation, (b) the 
interest mani-
fested by the people of the community in 
the value to them
of the pine and the importance of protecting 
it as the source
58
of future revenue, (c) the assurance of the majority of the
owners that concerted action will be taken according to a
definite plan and purpose, and finally, if a demonstration is
desired, that local -facilities will be offered for its successful
prosecution.
If the owners of pine will consider the protection of their
timber from the standpoint of a common interest and will re-
alize the necessity for concerted action in the control work,
success will be assured.
Under certain conditions the U. S. Bureau of Entomology
may undertake the supervision of demonstrations in the con-
trol of the southern pine beetle where it is abundant and
threatening further damage and the owners in the locality will
guarantee the necessary cooperation.
It will help much in future work if readers of this circular
will report to the Entomologist, Alabama Experiment Station,
Auburn, regarding the occurrence of this pest within the State
as it may be known to them.