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Historic, archived document 


Do not assume content reflects current 
scientific knowledge, policies, or practices. 


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V. 


CIRCULAR NO: 32, SECOND SERIES—REVISED EDITION. 


United States Department of Agriculture, 
DIVISION OF ENTOMOLOGY. 


THE LARGER APPLE-TREE BORERS. 


Among the most troublesome of the insect pests with which the 
fruit-growers of the United States have to deal are two species of 
boring beetles known, from the appearance of their larve, as the 
round-headed and flat-headed apple-tree borers. In addition, there 
is another species called the spotted apple-tree borer, after the adult 
form, and to distinguish it from the round-headed borer, which it 
closely resembles. The two species first mentioned are common and 
injurious throughout a wide extent of country—the former to seed 
fruit trees, the latter also to stone fruit, as well as to a great variety 
of forest and ornamental trees; the third is a comparatively rare 
insect and rather exceptionally injurious so far as known. 


THE ROUND-HEADED APPLE-TREE BORER: 


(Saperda candida Fab.) 


Fig. 1.—Saperda candida: a, larva. from side; hb, from above; c, female beetle; d, pupa—all 
enlarged one-third (original). 


INTRODUCTORY REMARKS AND DESCRIPTION. 


The round-headed uapple-tree borer is next after the codling moth, 
the worst enemy to apple culture in America. 

The first intimation that the grower may have of the presence of 
this borer in his trees, unless he be forewarned, is in their retarded 
srowth and the sawdust-like castings, consisting of excrementitious 


2 


matter and gnawings of woody fiber, which the larvee extrude from 
openings into their burrows. This manifestation is usually accom- 
panied by more or less evident discoloration of the bark, and, in early 
spring, particularly, slight exudation of sap. 

The parent of this borer is a beautiful beetle, measuring from 
three-fourths to nearly an inch in length, the male being percep- 
tibly narrower than the female. The antenne are long, stout, and 
many-jointed, being somewhat shorter than the body of the insect 
itself. These organs and the legs are gray, the under surface of the 
body and the head are silvery white, and the upper surface is light 
yellowish brown with two longitudinal white stripes extending 
through the thorax and elytra or wing-covers to the tip, as shown in 
the accompanying illustration (fig. 1 ¢). 

The larva when mature measures from three-fourths to a little 
over an inch in length (22-26 mm). It is fleshy and somewhat 
erub-like in appearance, cylindrical in form, and light yellow in 
color. The head is darker, particularly about the mandibles, which 
are nearly black. The first thoracic segment is large and broad and 
bears on its summit numerous small tubercles, placed close together. | 
The remaining joints of the body are narrower, the constrictions 
between them being deep and conspicuous. The first seven abdom- 
inal segments bear on the upper surface of each a peculiar elevated 
process, as shown at figure 1, 6. It is destitute of organs of loco- 
motion. 

The pupa, illustrated at d, is nearly as long as the adult insect, 
which it resembles in a superficial manner, the head being bent down 
toward the breast, and the legs and long antennz folded upon the } 
ventral surface. Its color is similar to that of the larva. 

Saperda candida was given its specific name by Fabricius in the 
year 1787, and was again described as new by Thomas Say, in 1824, 
under the name of S. bivittata, who remarked at the time upon its 
being injurious to the apple tree by boring into the wood. 


DISTRIBUTION. 


This species is native to this country and present in injurious num- 
bers in practically every State of the apple-growing region east of | 
the Rocky Mountains. It inhabits, like so many other injurious | 
insects, the upper austral and transition life zones, comprising the — 
better agricultural portion of all, except the extreme southern States. 
It has been reported to occur in one locality, Agricultural College, | 
Miss., which lies in what is considered the lower austral zone. As with 
many other injurious species again, it is in the older States, particu- 
larly New England and New York, where orchards have been long 
established, that injuries are most pronounced. Until recently this 


3 


species was not known as especially injurious about the District of 
Columbia, but at the present time it has become very abundant and 
destructive, whole orchards of both young and mature trees having 
succumbed to its ravages. 

Its known distribution as shown by published and unpublished 
records, in the possession of this office, includes Canada, all of New 
Kngland, New York, New Jersey, Pennsylvania, Delaware, Mary- 
land, Virginia, West Virginia, District of Columbia, Ohio, Illinois, 
Michigan, Iowa, Missouri, Kansas, and restricted localities in Texas, 
Alabama, and Mississippi. 


FOOD PLANTS AND NATURE OF INFESTATION. 


This borer is practically limited in its food supply to the apple and 
kindred woody plants. It is most injurious to quince and apple, and 
somewhat less troublesome to pear. It also infests crab apple and 
thorns of different species, mountain ash, choke-berry and June- 
berry, in short practically all except one or two kinds of the trees 
and shrubs belonging to genera now included in the restricted 
family of Pomacez. The wild plants are its natural food, but cer- 
tain varieties at least, although often inhabited by this insect, are for 
some reason not so susceptible to injury by it as our cultivated trees. 

This species inhabits more particularly the base of the trunk of 
trees, often being found below the surface of the earth, especially in 
young nursery stock. It is to such trees that it is most injurious as 
it soon works around the tree, separating the wood from the bark, 
interfering with the flow of sap and producing the effect of girdling, 
a result which is very apt to be produced even when no more than 
two or three larvee occur upon the same tree. Very frequently 
four or five larvze dwell together in a single small tree and in a short 
time injure it entirely beyond recovery. In old trees larvee occur 
somewhat higher up the trunk, in exceptional cases at a distance of 
several feet from the base or even, still more rarely, in the lower 
limbs; but as a rule they are seldom found except within a foot or 
two of the base. Trees of all sizes are frequently killed or so weak- 
ened that they are unable to mature a full crop of fruit. 

The experience of many years shows that injury follows where 
grasses, weeds, or other rank vegetable growth are permitted to accu- 
mulate about the trunks of the trees; since the beetle, like all noc- 
turnal insects, naturally seeks concealment, and the conditions thus 
afforded are most favorable for its attack on cultivated plants. 


LIFE HISTORY. 


The beetles make their first appearance of the season late in May 
and in June, according to locality, coming forth from the trunks of 
the trees in which they have bred during the night, at which time 


~ 


the species, being nocturnal, may be seen in flight. During the day 
the beetles hide away in some secluded place under leaves or in simi- 
lar situations on the trees which they inhabit. 

Soon after their first appearance the sexes mate and eggs are 
deposited. The female first makes an incision in the bark, whether 
by means of her mandibles or ovipositor is not plain, causing it to 
split slightly, then turning head upward, places an egg under the 
bark nearly a quarter of an inch from the incision, accompanying 
the deposition by the extrusion of ‘‘a gummy fluid which covers and 
secures it to its place and usually fills up the aperture. In young 
trees with tender bark the egg is usually thoroughly hidden while in 
older trees it is sometimes so shallowly imbedded as to be readily 
seen.” 

‘“The egg is pale rust-brown in color, one-eighth of an inch long, 
one-third as wide at the middle, flattened so as to have a depth of 
about one-third the width.” Its shell is fairly tough and resistant, 
not sculptured and sufficiently plastic, when laid, to receive impres- | 
sions from the woody fibers between which it is forced. Oviposition 
has been observed from June to September in a single locality (Law- 
rence, Kansas) but June is the month in which most of the eggs are 
laid.’ Fitch and others observed the beetles in the trees, near Albany, 
N. Y., as early as April. 

The period of the egg from the time it is laid until it hatches rests 
upon the statement of Mr. EK. W. Junkins that a young borer larva 
was observed July 7 from eggs” that were deposited June 15, which 
would give a period of twenty-two days. 

The larvee soon after hatching tunnel under the bark and feed 
upon the sap-wood, gradually working their way upward and after- 
ward downward, usually, particularly in young trees, remaining | 
within a short distance of, or below the surface of, the ground. By 
the beginning of the second year the larve, according to recent | 
observations conducted by the writer, attain an average growth of 
about five-eighths of aninch. The larval growth will naturally vary 
according to temperature, moisture, and quantity of food available 
for consumption, and other conditions. With the approach of cold 
weather the larvee cease feeding, but with the beginning of warm 
spring weather—in the District of Columbia as early as the latter 
days of March—they again commence, forcing their excrement and | 
castings consisting of gnawed particles of wood out through holes 
which they make in their burrows. By the end of the second year 
the larvee have increased considerably in size and have now pene- 
trated deeper into the solid heart-wood, their burrows being closely 


1 Above quotations from account by Riley in New York Weekly Tribune, Feb. 
20, 1878; Kans. Hort. Rept. for 1879, pp. 196-201. 
*New England Homestead, January 3, 1885. 


5 


packed behind them with castings. The third year the larve 
enaw outwards to the bark, form a pupal cell with the assistance of 
their castings and, with their heads pointing toward the bark, trans- 
form to pupe. With the approach of May and June they cut their 
way out by means of their powerful mandibles and issue through 
a round hole as mature beetles. The period of the pupal stage does 
not appear to have come under observation hitherto. <A. larva was 
observed by the writer at the Department of Agriculture that pu- 
pated May 11, and appeared as adult May 30, which gives nineteen 
days for this period; weather seasonable. 


NATURAL ENEMIES. 


Concealed as this insect is during its three years of existence in its 
preparatory stages it is nevertheless a prey to natural enemies which 
seek and devour it in its haunts under the bark. Of this number 
are woodpeckers and hymenopterous parasites. Of the latter only a 
single species is known to the writer, Cenocewlius populator Say.* 


METHODS OF CONTROL. 


After borers have once entered a tree there is no better remedy 
known than to cut them out with a knife or other sharp instrument. 
In the treatment of this insect an ounce of prevention is worth sev- 
eral pounds of cure. Cutting the borers out, unless practiced with 
the greatest care, is apt to result in injury, and it is far better to 
prevent the parent insects from depositing their eggs upon the tree. 
This is not difficult of accomplishment, as oviposition is practically 
confined to two months in a single locality, usually June and July. 
The best preventives are impenetrable substances placed about the 
trunk, and various washes of a repellent nature. 

Cutting out by hand.—Little has been gained in the line of direct 
remedies for this borer until very recent years. The early writers 
had nothing better to advise than cutting out the larva, either with 
a knife or gouge, or killing them by the insertion of a wire into their 
burrows. These remedies were in use early in the present century 
and are still the ones most often practiced. It is no uncommon 
thing to find four or more larve in a single small trunk and the cut- 
ting out of all of them, if not practiced with the greatest caution, is 
apt to result in the girdling of the tree, if, indeed, this has not already 
been accomplished by the combined attack of the borers themselves. 
It would seem superfluous to add that it is best to cut the borers out 
as soon as detected. Their presence may be known by a little experi- 


1 Mentioned in Insect Life, Vol. III, p. 59, as Promachus saperde Riley MS. 


6 


ence, some persons, the writer is informed, being so expert in detect- 
ing their exact location as to be able to kill them with a knife thrust 
or by the puncture of an awl or other sharp instrument. The fruit- 
grower should institute a practice of inspection that the borers may 
be removed as often as found. 


To assist the tree to recuperate after it has been girdled a bridge 
or two should be made by splitting a piece of apple twig (say, of an 
inch or two in thickness), cutting it diagonally on the inside, and 
applying to the surface at the base of the tree. It should then be 
tied on and grafting wax applied to each end, after which a fertilizer, 
preferably fresh cow manure should be applied and the whole banked 
over with earth. It is also well to keep the tree watered for a few 
weeks after treatment whenever this is practicable without too great 
inconvenience. 

Mechanical preventives.—This is one of the borers that can 
readily be controlled by different sorts of mechanical barriers placed 
about the base of the tree. For this a few thicknesses of newspaper 
wrapped rather loosely about the trunk and extending about two feet 
from the base are all that is necessary. This covering should be tied, 
by preference with cord, which will readily yield or break with the 
natural expansion of the tree inits growth, and also be tightly fastened 
at top and bottom and hilled up with earth so that the beetles can not 
obtain access to the tree from below. From the top of this covering 
upward it is best to use some deterrent alkaline or carbolated wash. 
Instead of newspapers, wire gauze or mosquito netting may be used, 
and should be put in place, so as to loosely encircle the tree, that the 
beetles may be unable to successfully deposit their eggs between its 
meshes and that the growth of the tree may not be hindered. Both 
have been successfully employed for a long period of years, and there 
is abundant testimony to their value. If the netting or paper be put 
in place early in May, it will not only prevent the beetles from ovi- 
positing during the next two months but will also keep the insects 
which might be present in the trunk from issuing and they will die 
in their burrows without being able to lay fertilized eggs. The 
paper wrapping must be removed each season, but the wire netting 
will last for several years. It is safe to remove either, ordinarily, 
after the first of September. 

Hydraulic cement mixed with skim milk, recently advised by Dr. 
J. B. Smith as a remedy for the peach-tree borer, should prove 
equally effective against this apple-tree borer. It could be applied 
with less trouble than paper bands. 

Protective washes.—Any one of several washes in general use 
against boring insects may be used as deterrents. A good alkaline 
wash is prepared of soft soap reduced to the consistency of thick 


Ky 
‘ 


paint by the addition of caustic potash or washing soda in solution. 
A good fish-oil, or whale-oil soap or common soft soap are often used, 
and in some cases any one of these is sufficient to deter the insects 
from depositing their eggs. The alkaline wash may be carbolated, 
if desired, by the addition of crude carbolic acid, at the rate of 1 
pint to every 10 gallons of the wash. Such a wash, it should be 
borne in mind, not only affords protection against this and other 
borers, but against scale and fungous diseases at these points, and is, 
moreover, of positive benefit to the tree. Caustic potash fish-oil 
soaps are among the best for insecticides. 


Whatever wash is used should be applied thoroughly, and in 
localities where apple-tree borers are unusually troublesome the 
larger branches should also be covered as far as possible. The wash 
may be best applied with a whitewash brush and should be renewed 
at intervals of two to four weeks, as found necessary, the first appli- 
cation being made before the appearance of the insects in May or 
June and again during July. 


It is well to scrape old trees to remove the dead bark-scales, care 
being taken not to cause any abrasion. Scraping is best done some 
time before the application of the wash that the wounds that might 
be made shall have opportunity to heal before the appearance of the 
beetles. 


The mature beetles are shy, and so seldom seen on this account, 
that it is doubtful if any method of destroying them is feasible. 
They are attracted to lights at night to some extent, and some meet 
their end in this way. 


Kerosene as a remedy.—A great variety of substances has been 
recommended to kill the borers in the trees, but up to the present 
time only a few have given satisfaction. For the benefit of those 
who have not had experience with this borer it may be necessary to 
state that it is of no avail whatever to inject kerosene or any other 
insecticide into the round holes made by the beetles in their escape 
from the trees. A correspondent of this Division, Mr. T. B. Ashton, 
who has had many years’ experience with this borer, states that 
there is no better way of effectually putting a stop to the depreda- 
tions of this and similar borers than in the use of kerosene applied 
freely wherever the castings of the larve are to be seen protruding 
through the bark. The kerosene is absorbed by the castings and, 
carried by capillary attraction, permeates the entire burrow where it 
comes in contact with the larva, which soon succumbs. The amount 
of kerosene which it is necessary to use is so small that it does not 
endanger the health of the tree. 

Clean cultural methods.—Finally, clean culture, the best pre- 
ventive for insect injury of whatever kind, should not be neglected. 


8 


The nursery should not be started in new localities where crabs, 
thorns, June-berry, and other wild food plants of this species grow in 
great profusion nor in the vicinity of neglected orchards, nor should 
rank growths of weeds, grasses, bushes, and briars be permitted to 
accumulate about the trunks of the trees. When a tree is seen to be 
injured beyond recovery it should be taken out and destroyed by 
burning before the following spring, that the larve which it contains 
may not have an opportunity to develop and infest healthy growth. 


THE SPOTTED APPLE-TREE, BORER: 


(Saperda cretata Newm.) 


A very similar insect to the preceding both in appearance and in 
habits is the spotted apple-tree borer (Saperda cretata Newm.). The 
adult beetle is of nearly the same size and form as the round-headed 
borer, differing superficially by having two white spots on each elytron 
(fig. 2) instead of the longitudinal white lines 
which distinguish the latter (fig. 1c). The larva 
and pupa are so similar that no description need 
be made of them. Although the species has a 
fairly wide distribution, corresponding some- 
\ what closely to that of the common species, 
' specific injury by it has only been noted in two 
States, in Michigan by Prof. A. J. Cook and in 

Iowa by Prof. H. Osborn. In the former State 
female beetlovenlarsed this borer is reported as quite as common and 
TE rane grow destructive as Saperda candida. Its occur- 
rence is also recorded in Canada, Massachusetts, New York, Penn- 
sylvania, Wisconsin, and Ohio, and there are specimens in the 
National Museum also from Northern Illinois and Texas. It has only | 
been observed injuring apple and wild crab, but its occurrence has 
also been noted on June-berry and thorn. According to Osborn the 
“egos are evidently laid in pairs, half an inch or more apart, along 
the branch, the larve of each pair upon hatching working in opposite 
directions around the branch, at first just beneath the bark, after- 
ward (probably after the first year) entering the hard wood.” 


The remedies for this species are the same as for the preceding 
with the extra precaution that the larger branches also be protected 
by the wash applied. 


Nortr.—A third species of Saperda, fayi Bland, has similar habits and is likely 
to attack apple and similar cultivated pomaceous trees, but is thus far known 
only on thorns. A very full account of this species was published by the late 
Dr. Hamilton (Can. Ent., Vol. XX, pp. 6-8). 


9 


THE FLAT-HEADED APPLE-TREE BORER. 
(Chrysobothris femorata Fab.) 


GENERAL APPEARANCE AND NATURE OF INJURY. 


A much less dangerous, though more abundant, insect than any of 
the preceding, is the flat-headed apple-tree borer. It belongs to a 
different family of Coleoptera, the short-horned wood-borers or metal- 
lic beetles of the family Buprestide, and differs remarkably from the 
preceding in all its stages as well as in its habits and life history. 

The adult insect (represented at 0, fig. 3) measures from a little less 
toa little more thana half inch in length. It is flattened above, resem- 
bling somewhat a snapping beetle, but it is not provided with jump- 
ing organs like the Elateride. The antenne are short and serrate, 
the eyes large and conspicuous, and the forelegs are armed in 
front with a conspicuous tooth. 
The upper surface of the body is 
dark metallic brown and fresh 
specimens are coated here and 
there with a powdery gray sub- 
stance, which is easily rubbed off. 
The wing-covers are ornamented 
as shown in the illustration, and 
underneath, as may be seen when 
the insect is in flight, the body isa 
bright metallic greenish blue. The Fig. 3.—Chrysobothris femorata: a, larva ; 
under surface is coppery bronze. AU ISE SUE LOBEDES (Uy UIE USING BEE 
The males are smaller and may 
further be distinguished from the females by their green heads as 
well as by other characters (see fig. 3, ¢). 

Unlike the round-headed borer the present species is diurnal in 
habit, being most active in the heat of the day and commonly found 
on prostrate trees and logs or on injured trunks basking in the sun- 
light. The beetles are active creatures, running rapidly and flying 
readily. 

This species attacks by preference diseased or dying trees, inhabits. 
all parts of a tree from the base of the trunk to the limbs, and is not 
restricted in its ravages to fruit trees, but attacks also a variety of 
deciduous trees. | 

In all these respects it differs from the round-headed borer, but 
agrees with the latter in that it is injurious chiefly to young trees, its 
injuries being practically confined to newly transplanted nursery 
stock and to trees which have been weakened through any cause, 
such as careless pruning, or insufficient nourishment due to poor soil or 
drouth. There is a difference of opinion as to the nature of damage, 
some writers taking the stand that healthy trees are not injured at 


10 


all. Itisa well-known fact that many forms of boring insects prefer 
injured plants but when this is wanting do not hesitate to attack 
perfectly sound growth, and records show conclusively that the 
present species is included in this category. The general opinion is 
that trees suffering from ‘‘sun scald” are most subject to attack, 
and the opinion has been expressed that injury known under this 
name is in reality due to the work of this species of borer. The 
beetle is essentially a sun-loving species and deposits its eggs prac- 
tically exclusively on the southern or southwestern sides of standing 
trees or on recently felled logs that are exposed to direct sunlight. 
Observation shows that it is doubtful if the young larve would be 
able to withstand the strong flowing sap of vigorous trees. 


Infestation may be detected by the discoloration of the bark. 


A list of its recorded food plants includes, among orchard trees, 
apple, pear, peach; and of shade and forest trees, mountain ash, 
oak, maple, box-elder, hickory, chestnut, sycamore, horse-chestnut, 
linden and willow. To this list should be added plum and cultivated 
redbud (Cercis japonica), from which the species has been reared 
by the writer, and the currant.’ 3 

Cherry, beech, and white birch are probably food plants although 
the beetle has not been reared from them, and elm, tulip, and cot- 
tonwood have been mentioned as such, but on what authority is not 
clear. Oakis without doubt the favorite natural host tree. 


The larva differs greatly from that of the round-headed borer. 
Its name of flat-headed borer is derived from the peculiar flat expan- 
sion of the second thoracic segment, the one just behind the head. 
In color it is hght yellow and in length it measures nearly twice that 
of the mature insect. It habitually rests in a curved position, more 
bent usually than shown in the illustration (fig. 3, a). The pupa (d) 
shows the form of the future beetle and is of the same yellow color 
as the larva. 


This species inhabits practically the entire United States and the 
southern portion of Canada, being like the preceding, a native of 
North America and injurious year after year. 


NATURAL HISTORY AND HABITS. 


The beetles make their appearance about the same time as the 
round-headed borer, in regions infested by both species, in the 
principal apple-growing regions of the northern States after the 
middle of May, and continue through the month of July, and, it 
is said, even into September, the female depositing her eggs upon 


1F. H. Hillman, Nevada Experiment Station, Bul. 36, p. 18. 


lh: 


the trunks or branches of trees destined to be the future food of 
the larva, in cracks and grooves or under bark scales. Several 
eggs are most frequently found together. The eggs are yellow in 
color, irregularly ribbed, and about one-fiftieth of an inch in length.’ 
The larva differs from the round-headed borer in that it requires 
only a single year for its development, pupation occuring in the 
spring shortly before the appearance of the beetles. It differs also in 
its manner of work, living for the most part just beneath the bark, . 
where it excavates broad, flat, and very irregular channels, but 
sometimes entering more deeply into the sap-wood. Like many other 
borers it often girdles a small tree, a single individual being capable 
of killing a small tree in this manner. As it approaches maturity it 
generally eats deeper into the solid heart-wood, but in spring time, just 
before transformation, it works back again into the bark, and there 
constructs its pupal chamber. In the pupa state it is said to remain 
for about three weeks,’ when the beetle cuts its way out, leaving an 
elliptical exit hole in the bark, which distinguishes its work from 
that of the round-headed borers, which make round holes in their 
exit. These holes correspond to a cross-section of the beetle which 
makes them. In the North the winter months are passed as larvae, 
but farther south, in the District of Columbia, according to recent 
observation, pupation may take place as early as November of the 
first year.* 
NATURAL ENEMIES. 


Among natural enemies, woodpeckers are effective destroyers of 
this species, as are also ants, which devour larve and pups under 
the bark. A number of parasitic insects also prey upon it and assist 
greatly in restricting its too great abundance.’ 


REMEDIES. 


The remedies advised for the round-headed borer are also of value 
and are generally employed against the present species. It is neces- 
sary, however, that deterrent coverings and washes should be applied 
farther up the trunk and to as many branches as can be conveniently 
reached. As this, however, necessitates additional labor and extra 
expense, other preventive measures are recommended. 

Trap wood for the beetles.—For this purpose any sort of tree 
known to be freely attacked by this borer, e. g., oak, maple, or any 


rw) 


1C. V. Riley, Proc. Ent. Soc. Wash., Vol. III, p. 92. 

* The list includes the Braconids, Bracon charus Riley and B. pectinator Say; 
Spathius pallidus Ashm.; the Ichneumonids, Labena apicalis Cr. and L. gral- 
lator Say ; and one or more species of Chalcidide, noticed by Fitch as occurring 
in New York, and by Riley in Missouri, 


12 


fruit tree, may be used. If a few limbs or trunks of newly felled 
trees be placed at intervals, say, of thirty or forty feet, on the out- 
skirts of orchards, where they would be freely exposed to the sun, 
the beetles would be attracted for the deposition of their eggs, and 
all that would then be necessary would be to destroy the trap wood 
by burning before April or May of the following year. This plan 
has not been practically tested, but the writer has no doubt that it 
would prove useful in securing immunity from this pest in the 
orchard, provided that no diseased fruit trees be left for food. 

Cultural carefulness.—Careful, clean methods of cultivation are 
essential as a measure of protection, and involve the cutting out of 
dead, dying, and injured deciduous forest and shade trees known to 
be chosen as food by this beetle, as well as orchard trees. Care 
should be exercised in transplanting, and especially in pruning, and 
the use of fertilizers should not be neglected, that the trees may be 
thrifty and better able to withstand attack. Proper regard for these 
measures should give practical exemption from injury. 

KF. H. CHITTENDEN, 
Approved : Assistant Entomologist. 
JAMES WILSON, 
Secretary. 


WASHINGTON, D. C., August 30, 1902. 


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