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U.S. DEPARTMENT OF AGRICULTURE

DIVISION OF ENTOMOLOGY.

Bulletin NO. 6.

THE IMP( >KTED

ELM LEAF-BEETLE

ITS HABITS AND NATURAL HISTORY,

MEANS OF COUNTERACTING ITS INJURIES.

W A SH [KG TON :

GOV BE n m 1: \ I run t im;

1S85.

\4T*\Tt Bull. 6

Department of Agriculture,

Division of Entomology,

Washington, D. C, April 25, 1885.
Sir : I have the honor to submit for publication Bulletin No. G, from
this Division. The Imported Elm Leaf-beetle (Galeruca xanthomekena
Schrank) has committed serious ravages upon the Elms in many States
during the past few years, and numerous inquiries have already been
made about it the present year. In my annual report as Entomologist
for the year 1883, 1 published a full account of this insect, but this report
is now no longer to be had. I have therefore deemed it best to reprint
account referred to in bulletin form for ready distribution to inquirers.
Respectfully,

C. V. RILEY,

Entomologist.
Hon. Norman J. Colman,

Commissioner of Agriculture.

:',

THE IMPORTED ELM LEAF BEETLE

Galeruca xantkomel&na* Schrank.]
Order Coleoptee a ; family Chbysomexed i.

-

. .t!y pnlargi

•■''same: /'. pupa (enlarj

The depredations of this pest have now become widely extended
throughout the Northeastern States, rendering unsightly and almost
worthless th< valuable shade trees of our eities— the elms, a-

it< injuries are so tar unknown in the Mississippi Valley, the blighted
appearance of tin- elms on tin- Department grounds in midsummer, and
especially of the European varieties, at once attracted our attention
when we first came to Washington, and a series of experiments was
in with a view of checking the i >f the insect. Tin- excel-

Forst., and G. Mmmrie$tu Fahr. In Crotel

ranthomejcena.

6 THE IMPORTED ELM LEAF-BEETLE.

lent opportunities thus offered for experiment and study have siuee
been improved, and, with some prefatory passages in relation to the
history and habits of the beetle, we will give the practical results
reached.

AN IMPORTATION FROM EUROPE.

This beetle has done great mischief in the Old World, especially in
Germany and France, and it is very important that the public know
the best method of coping with it here. According to Glover, it was
imported as early as 1837. Its distribution was formerly confined to
limited areas near the coast, and its earlier attacks were notably about
Baltimore and Xew Jersey.

HABITS AND NATURAL HISTORY.

The general characteristics of this insect have been pretty well studied
abroad. Mr. E. Heeger* has given au excellent account of its life-his-
tory, with a detailed description of the larva, and figures illustrating
larva and pupa and anatomical details. More recently M. Maurice
Girardt has given a rather poor wood-cut illustration of the insect and
its work, with the leading facts concerning its nomenclature and nat-
ural history as observed in Europe. Biological notes on the insect
have also beeu given by LeinweberJ and Kollar. §

In our eountry the life-history of the insect and its injury have been re-
ferred to by Harris, Fitch, Morris, Walsh, and ourselves, while the agri-
cultural papers contain numerous references to the injury inflicted by the
insect. The perfect beetle has often been described in systematic works
on Coleoptera.

For these reasons we deem it unnecessary to enter here into a detailed
description of the beetle and its earlier stages, but content ourselves
with pointing out the more obvious characters, alluding to such facts of
the life-history as are necessary to a full understanding of the nature
of the remedies to be applied for this pest.

The eggs are deposited in an upright position upon the under side of
the leaves (Fig. 1 a), always in a group, consisting generally of two, rarely
three, more or less irregular rows. The individual eggs are close together
in each group (Fig. 1 e, magnified), and so firmly fastened to the leaf
that they can only be detached with great care without breaking the thin
and brittle shell. The number of eggs in each group varies from four
or five to twenty or more. Very rarely only three eggs are seen in one
group, but we never found less than that number. The egg itself is
oblong oval, obtusely, but not abruptly, pointed at tip, of straw-yellow

* Seventeenth contribution to the natural history of insects. Sitzungsberichte der
kais. Ac. Wiss., Wien, 1858, vol.29, p. 100-120, 6 pi.

tNote sur la Galeruque de l'orrae. Bull. d'Inseetologie Agricole, 1878, III, pp.
113-116.

t Verhandlungen zool.-bot. Ges.,Wien, 1856, VI; Sitzb., pp. 74-75.

§ Op. cit,, 1858, VIII; Abh., pp. 29-30.

THE IMPORTED ELM LEAF-BEETLE. i

color, its surface being opaque and beautifully and evenly reticulated,
each mesh forming a regular hexagon, as shown, highly magnified, in
Fig. If. The form of the eggs is not quite constant, some of them,
especially those in the middle of a large group, being much narrower
than others. The duration of the egg state is about one week.

The general shape of the larva is very elongate, almost cylindrical, and distinctly
tapering posteriorly in the early stages, but less convex and of nearly equal width
when mature. The general color of the young larva is yellowish-black, with the black
markings comparatively larger and more conspicuous, and with the hairs arising from
these markings much longer and stifferthan in the full-grown larva. With each con-
secutive molt the yellow color becomes more marked, the black markings of Less
extent and of less intense color, and the hairs mnch shorter, sparser, and lighter in
color. A nearly full-grown larva is represented in Fig. 1 g, and in this the yellow
color occupies a wide dorsal stripe and a lateral stripe each side. The head (except-
ing the mouth-parts and anterior margin of the front), the legs (excepting a ring
around the trochanters), and the posterior portion of the anal segment are always
black. The first thoracic segment has two large black spots on the disk, of varying
extent, and often confluent. The following segments (excepting the anal segment)
are dorsally divided by a shallow transverse impression into two halves, and the black
markings on these halves are arranged as follows : two transverse dorsal markings,
usualty confluent, as shown in our figure ; two round and sublateral spots ; the tips of
the lateral tubercles are also black. The abdominal joints of the ventral surface have
each a transverse medial mark, and two round sublateral spots of black color. Stig-
mata visible as small umbilicate spots between outer sublateral series of dorsal mark-
ings and lateral tubercles. The'yellow parts of the upper side are opaque, but those
of the under side shining. The black markings are polished, piliferous, and raised
above the remaining portions of the body.

The larvae are destructive to the foliage from the month of May until
August. They have about two weeks of active life between the egg
and pupa states. During this time they prey upon the leaves, which
become skeletonized, leaving the venation and commonly a certain
portion of the flesh of the leaf, which becomes rust-brown. They un-
dergo four molts, respectively observed at Washington on July 15 (at
hatching), 20, 23, and 29 (pupation). When full-grown they descend to
the ground and change to pupa under whatever shelter is near to the
base of the tree.

The pupa is of brighter color than the larva, oval in shape, and
strongly convex dorsally. It is sparsely covered with moderately long
but very conspicuous black bristles, irregularly arranged on head and
thorax, but in a transverse row on each following segment. The pupa
state lasts about from (j-10 days.

The perfect beetle (Fig. 1 o, natural size; /,-, magnified | resembles somewhat in ap-
pearance the well-known striped Cucumber-beetle (Diabrotiot rithita^, hut is at ones
distinguished by the elytra not being striate punctate, but simply rugose, the sculpt-
ure under high magnifying being represented in Fig. 1 /. The color of the upper side
is pale yellow or yellowish-brown, with the following parts black : on the head a
frontal (often wanting) and a vertical spot: three spots on the thorax : on the elytra
a narrow stripe along the suture, a short, often indistinct scutellar stria each side.
and a wider humeraj stripe not reaching the tip. Under side black, pro and meso-
steruum and legs yellow, femora with a black apical spot. Upper and under side
covered with very tine, short, silky hairs. In newly-hatched individuals the black
markings have a greenish tint; the humeral stripe varies in extent.

O THE IMPORTED ELM LEAF-BEETLE.

Tlie beetle assists the larva in its destructive work, but, as usual in
suck cases, the damage done by the perfect insect is small when com-
pared with that done by the larva. There are three or four annual
generations of the insect, according* to the character of the season. In
the month of September the beetles prepare for hibernation, seeking
shelter in hollow trees, in the ground, under old leaves, &c, and remain
dormant until the following spring.

REMEDIES.

M. Girard says :

There is do other means of destruction than to jar the branches over cloths to col-
lect the larvae and adults which fall. It is also possible when they are on the ground
to distribute on them boiling water or steam, or even quicklime or solution of sulpho-
carbonate of potassium.

In our own country much more has been accomplished toward prac-
tically combating this insect.

In the U. S. Agricultural Eeport of 1807, Glover suggested the use of
oil and tar gutters and other barriers surrounding the base or the body
of the tree, devices similar to those used against the Canker Worm and
Codling Moth. He then and afterward (1870) recommended "to place
around each tree small, tight, square boxes or frames, a foot or 18 inches
in height, sunk in the earth : the ground within the inclosure to be cov-
ered with cement, and the top edge of each frame to be covered with
broad, projecting pieces of tin like the eaves of a house or the letter T,
or painted with some adhesive or repellant substance, as tar, &c. The
larvae descending the tree, being unable to climb over the inclosure,
would change into helpless pupae within the box, where they could daily
be destroyed by thousands. Those hiding within the crevices of the
bark of the trunk could easily be syringed from their hiding places."
(TJ. S. Agricultural Eeport, 1870, pp. 73, 74.) These boxes were carefully
tested at this Department, and they worked as described. While coal-
tar and other adhesives were recommended, we have found scalding-hot
water most convenient for destroying the insects that accumulate in the
inclosure or upon the ground elsewhere. Where branches are low and
droop near the ground some of the larvae descend the wrong way and fall
off but shade trees should not be allowed to grow in this low, drooping
manner and under all ordinary circumstances, where the branches are
not severely jarred to encourage the insects to drop, the larvae will de-
scend by the trunk and become captured in the devices here noticed.
}Lr. Glover regarded the pupa state as the most favorable in which
to kill the insect, as it can then be easily crushed or scalded. Concern-
ing the tobacco treatment, he adds that "syringing the trees with strong
tobacco water has been tried with some good effect, but the larvae not
touched by the fluid are merely knocked down by the concussion, and,
if nearly ready to change into pupae, effect their transformation where
they fall."

THE IMPORTED ELM LEAF-BEETLE. 9

In this connection we cannot do better than quote what we published
in L880* in reply to certain statements by Dr. J. L. LeConte, as fol-
lows:

Aii'-nt Galeruca zanthomelama, which is becoming more destructive each -
scar to the .-hade elms in our northern towns, a correspondent mentions the following
facts :

1. The trees arc not all attacked at the saint- time, but the insect seems to break
out from a center, gradually destroying the more remote trees, so that isolated
remain comparatively free.

•2. After applying a band (saturated with fish-oil, petroleum, &%.) to some trees
which were about half denuded, found hundreds of the worms stopped both in ascend-
ing and descending the trees.

He also propounded the following query :

3. Do the beetles hibernate in the ground, so that they can be poisoned, or are they
perpetuated only by the eggs on the trees '

Allow me to add the following subjects for investigation as necessary to the devis-
ing of proper remedies against this foreign invader :

4. How soon do the insects appear in the spring: how rapidly do they prop,,,
and what time is passed in each stage of development .'

5. Are the larva- and beetles eaten by insectivorous birds ; or are they protected by
offensive secretions, as is the case with Doryphora 10-lineata, Orgyia leucoaiigma, and
several other noxious insects .'

t>. "What proportion of the brood hibernates, and in what stage, pupa or perfect in-
sect, and when

If the materials for furnishing answers to these questions are not vet within your
reach, will you kindly direct the attention of some of your trusty observers to the
subject, so that persons interested in the preservation of the shade trees which .
justly esteemed may be properly instructed as to the measures to be adopted during
the next summer.

Very truly, yours,

J. L. LkCONTE,

Philadelphia, Pa.

above inquiries \\ ere received from our esteemed correspondent some timesiuce,
and we employ them as a ready means of giving our experience with the beetle.

For the benefit of the general reader it may be remarked that the natural history
of this Elm Leaf-beetle is quite similar to that of the well-known Colorado Potato-
beetle and of the Grape-vine Flea-beetle. The only deviation in the Elm Leaf-beetle
is in the mode of pupation, which rarely takes place in the ground, unl.
very triable, but at the base of the tree or under any shelter that may present itself
near the trees, such as old Leaves, grass, ^\ c,

(1.) The phenomenon hen- described i^ doubtless due to the gradual incred
spring from one or more females.

and 6.) Like most, if not all. Chrysoinelida, the Elm Leaf-beetle hibernates in the

perfect state. As places suitable for hibernation abound, any attempt —fully

fight this pest in winter time, with a view of preventing its ravages the subsequent

L, will prove fruitless. A large proportion id" the hibernating U .btlesa

perish, since the insect is comparatively scarce in the earlier part of the season.

(4 and 5.) The beetles il.\ at spring opens, and we have observed the first

larva- early in May. in Washington, 1>. ('.. or some time after the elm leaves are fulh
developed. The ravages of tin' insect begin to be apparent with the Beco
tion of larvae, which appear in June.

can Entomologist, December, L88

10 THE IMPOETED ELM LEAF-BEETLE.

In 1878 we made rnany notes and experiments on the species, and the development
of the third and most injurious generation occupied about one month. The numerous
pupa? which in the latter part of August were to he found under the trees were
mostly destroyed that year, partly by continuous wet weather prevailing at the time,
partly by the many enemies of the insect. Among these there are Platynus puncti-
formis and Quedins molochinus, which feed on the full-grown larvae when these retire
for pupation, and also on the pupae. The larva of a Chrysopa (probably C. rufilabris)
feeds upon the eggs of the Galeruca, Eeduvius novenarius sucks both beetles and larva?
on the leaves, while Mantis Carolina preys upon the beetle. Of the numerous other
insects found among the pupae under the trees, e. g., Tachyporus jocosus, sundry spiders,
myriapods, &c, 'several are doubtless enemies of the Galeruca, though we haveasySt
no proof of the fact. Many birds were observed on the trees infested by the beetles,
but the English Sparrow, which was the most'numerous, did not feed on the insect
in any stage of growth.

The only method of warfare against this pest recommended by European writers is
to jar the larva? down on to sheets, and then in one way or another to destroy them.
This may answer for young trees, but is then tedious and but partial. We found that
the quickest and most satisfactory way of destroying the insect and protecting the
trees was by the use of Paris green and water in the manner frequently recommended
in these columus, and London purple will evidently prove just as effectual and
cheaper. The syringing cannot be done from the ground except on very young trees,
though a good fountain pump will tbrow a spray nearly 30 feet high. Larger trees
will have to be ascended by means of a ladder and the liquid sprinkled or atomized
through one of the portable atomizers, like Peck's, which is fastened to the body, and
contains 3 gallons of the liquid.

The mode of pupation of the insect under the tree, on the surface of the ground,
beneath whatever shelter it can find, or in the crevices betweeu the earth and the
trunk, enables us to kill vast numbers of the pupie and transforming larva? by pour-
ing hot water over them. We found that even Paris-green water poured over them
also killed. If the trees stand on the sidewalk of the streets the larva? will go for
pupation in the cracks between the bricks or at the base of the tree, where they can
also be killed in the same way. This mode of destruction is, take it all in all, the
next most satisfactory one we know of, though it must be frequently repeated.

(2.) We have largely experimented with a view of intercepting and destroying the
larva? in their descent from the tree. Troughs, such as are used for Canker-worms,
tarred paper, felt bands saturated with oil, are all good and the means of destroying-
large numbers. Care must be taken, however, that the oil does not come in contact
with the trees, as it will soon kill them, and when felt bandages are used there should
be a strip of tin or zinc beneath them. The trouble with all these intercepting de-
vices, however, is that many larva? let themselves drop down direct from the tree and
thus escape destruction.

In conclusion we would remark that it is highly probable that Pyrethrum powder
stirred up in w^ater might be successfully substituted for arsenical poisons, but experi-
ments in this direction have not yet been made. From experiments we have made
with dry, unmixed powder, we found that it affects very quickly the larva, pupa,
and the perfect insect, but in order to be applied on a large scale and on large trees
the powder must of course be mixed in water. There is, however, no danger in the
judicious use of the arsenical liquids upon shade trees.

MORE RECENT EXPERIENCE AT THE DEPARTMENT.

The more recent experience in the destruction of this Galeruca on the
Department grounds may now be summed up, the experiments having
been intrusted to Dr. Barnard.

THE IMPORTED ELM LEAF- BEETLE. 11

Past history of the Elms in question. — According to Mr. William Saund-
ers, of this Department, these trees have been annually attacked by the
European Elm Leaf-beetle since they were planted ten years ago, and
about one year in three the injury has been severe, resulting in their
defoliation, while in other years, as in 1879 and 1880, there appeared
comparatively none. In some seasons a second or autumnal set of le
appeared after the trees had been stripped, and in certain of these in-
stances the second crop of leaves became eaten : but in all cases he
thinks the lives of the trees have not seemed to be endangered and they
soon repaired the damage done. His belief is also that the pest did nor
become gradually worse and worse through the series of years during
which it has been observed by him; still he regards the attack of 1 882
as worse than any known to him before on these trees or others, and
he has noticed the effects of this insect since 1850, first in its earliest
ravages about Baltimore, and later elsewhere.

Condition and Characteristics of the Grove in 1882 and 1883. — However
it may be for the past history or future desirability of certain trees in
the grove, in 1882 many exhibited various grades of feebleness, and some
had dying branches. Indeed, a few of them had a very unhealthy as-
pect the previous year also. Of course it can be claimed that their
unhealthy condition is due to other causes than the insects: and it should
be remembered that most are foreign species, each often represented in
two or more of its varieties. Here all grow on level ground, whereas
in a state of nature some belong to mountainous localities, others to
the damp climate of England, &c. Therefore, many of them are grow-
ing under abnormal conditions. They exhibit much variety in the
relative abundance, size, form, and texture of the leaves. There is also
great diversity in the density and form of branching.

Extent of Injury in 1882 and 1883. — All the varieties and specio <>t
elms in this grove, without exception, were preyed upon by the pest in
1882 and 1883. The insect, however, showed decided preferences for
certain individual trees, varieties, or species, stripping some completely
before doing more than very slight harm to the leaves of others, the
former becoming completely eaten in midsummer, the latter not until
toward the close of the season, or remaining only slightly damaged
until then. In 1882 the leaves were eaten faster than they could be
developed, and the insect continued abundant enough to prevent a
second crop of foliage until in November, when it became too cold for
the leaves and active insects to exist.

On these grounds the southeast side of each tree has suffered more
than the northwest half. This peculiarity has been very strongly pro-
nounced this year, 1883, on all the trees affected, and upon some exam-
ples far more markedly than upon others. This one-sidedness is
especially apparent in the trees which were the most severely eaten.
Some tiees show the southeast side completely devoured but the north-

12 THE IMPORTED ELM LEAF-BEETLE.

west side only half consumed and comparatively green. Such are aver-
age cases.

The inferences have been that the shade, dampness, and coolness of
the tree on the northwest side during the morning is too unhealthy for
the favorable development of the larvae or of the eggs deposited there ;
but whether this be true or not, the insect probably prefers to deposit
chiefly in the middle of the forenoon, and on that part of the tree which
is then warmest. This would give a greater number of the eggs at the
outset on the southeast side, as observation seems to confirm, and since
the young larvae do not migrate to any noteworthy extent, the one-sided -
ness described would result whether the northwest side were unhealthy
or not. The former explanation is most probably the correct one, as we
have noticed that the insect is less injurious during very wet summers.

Preferences of the Elm Beetles for certain Varieties and Species of Elms. —
The American Slippery Kim does not occur in this grove, but only one
native species, the common American Elm, Ulmus americana. This is
practically free from the ravages of the beetle, on which account it may
be preferred to the European species. It is tall, and has gracefully
arched branches, making it as ornamental as any European kind, yet
as a shade tree it does not equal the U. montana of the Old World. The
latter has a broader, denser crown, but the attack on it is considerable,
enough to leave the choice in favor of the American species.

U. montana seems the best European species grown here for shade,
since the other foreign elms here cultivated are not dense enough. This
applies to U. campestris, V. suberosa, V. effusa, and U. parvifolia (siber-
ica >. The last named is not attacked as much as the American. The
young larvae cannot develop on it, but die quite soon, without growing,
and they gnaw the leaves very little. The other foreign species men-
tioned are seriously eaten; the severest attack being upon the U. cam-
pestris, the favorite food of this insect.

As early as June 25, in 1883, this species was completely eaten and
biown in our grove, at which date the U. montana examples retained
more than half their verdure — in some individuals nearly all — and the
common American elm was perfectly green. The U. campestris is one of
the poorest elms for shade, and its total abolishment throughout the
entire country would probably lessen the assault on TJ. montana to a
comparatively unobjectionable extent. This measure should be insti-
tuted against the pest, and for the sake of the other species of elms.

Effects of arsenical Poisons on Insect and Plant. — Species of elms are
somewhat differently affected by the poison. When treated alike there
is always manifest some difference in the susceptibility of different elms
to the corrosive effects of the poison. Even individuals .of the same
species or variety are differently impaired. As a rule, those which suit
the insect best are injured most by the poison, and those which resist
the insect most withstand the poison best. The latter have coarser
foliage, with darker green color and more vigorous general growth; the

THE IMPORTED ELM LEAF-BEETLE.

former have more delicate foliage, lighter in cold]' and weight, appar-
ently less succulent.

Certain elms of the specie s U. campestris and other species which

overpoisoned, and shed most of their leaves in consequence in the last
of June, 1883, sent out a profuse new growth of leaves and twigs.
foliage fell gradually for three weeks, and this was somewhat prom
by the succeeding rains.

The larva' move from place to place so seldom that if' tin- leaves
imperfectly poisoned from the mixture being weakly diluted, or from its
application only in large, scattered drops, which are much avoided by
the larva*, they are not killed off thoroughly for several days, and in all
cases it requires considerable time to attain the full effect of the poison.
This result appears on the plant and on the insect. After each rain
the poison takes a new effect upon the plant and the pest, which indi-
cates that the poison is absorbed more, or is more active when wet, and
that it acts by dehydrating thereafter. Where the tree is too strongly
poisoned, each rain causes a new lot of leaves to become discolora
the poison or to fall. On some of the trees the discoloration appears in
brown, dead blotches on the foliage, chiefly about the gnawed places
and margins, while in other instances many of the leaves turn .yellow.
and others fall without change of color. The latter may not all drop
from the effects of poison, but the coloration referred to is without doubt
generally from the caustic action. The poison not only produces the
local effects from contact action on the parts touched by it, but follow-
ing this there appears a mere general effect, manifest in that all tie- fo-
liage appears to lose, to some extent, its freshness and vitality. This
secondary influence is probably from poisoning of the sap in a moderate
degree. When this is once observable, no leaf-eater thrives upon the
foliage. Slight overpoisoning Seems to have a tonic or invigorating
effect on the tree.

Preventive Effects of the Poison. — In this grove the elms that were
soned in 1882 were attacked in the spring of L883 less severely than 9
those which were not poisoned the previous year. This would seem to
imply that the insects deposit mostly on the trees nearest to where they
develop, and are only partially migratory before ovipositing. Tin
tack afterward became increased, probably by immigration and the
new generation, so that later in the season the trees were mostly in-
fested to the usual extent.

In the region of Washington a preventive application of poison should
be made before the last of May or first of June, when the eggs an
ing deposited and before they hatch. This will prevent the worms from
ever getting a start. By the preventive method the tree escapes two
kinds of injury : first, thai directly from the eating by the insect; second,
that which follows indirectly from tin4 deleterious effects of the pd i
on the plant, for its caustic effect is much greater where the lea\ es
been so gnawed that the poison comes in contact with the sap.

14 THE IMPORTED ELM LEAF-BEETLE.

Treatment with London Purple. — Already early in June the insect ap-
pears plentiful. On June 7, 1882, it was at work on all the trees, and
its clusters of eggs were numerous beneath the leaves. Some of the
trees had half of the leaves considerably gnawed and perforated by
larvje of all sizes, and by the adults. At this date fifteen trees, consti-
tuting the south part of the grove, were treated.

Preparation of the Poison. — London purple (one-half pound), flour (3
quarts), and water (barrel, 40 gallons) were mixed, as follows : A large
galvanized iron funnel of thirteen quarts capacity, and having a cross-
septum of fine wire gauze such as is used for sieves, also having vertical
sides and a rim to keep it from rocking on the barrel, was used. About
three quarts of cheap flour were placed in the funnel and washed through
the wire gauze by water poured in. The flour in passing through is
finely divided, and will diifuse in the water without appearing in lumps.
The flour is a suitable medium to make the poison adhesive. The Lon-
don purple is then placed upon the gauze and washed in by the remain-
der of the water, until the barrel is filled. In other tests the flour was
mixed dry with the poison powder, and both were afterward washed
through together, with good results. It is thought that by mixing in
this waj less flour will suffice. Three-eighths of a pound of London
purple to one barrel of water may be taken as a suitable percentage.
Three-eighths of an ounce may be used as an equivalent in one bucket-
ful of water. The amount of this poison was reduced to one-fourth of
a pound to the barrel with good effect, but this seems to be the mini-
mum quantity, and to be of value it must be applied in favorable
weather and with unusual thoroughness. With one-half or three-
fourths of a pound to the barrel about the maximum strength allow-
able is attained, and this should be applied only as an extremely fine
mist, without drenching the foliage.

Effect* of the Mixture. — The flour seems to keep the poison from tak-
ing effect on the leaf, preventing to some extent the corrosive injury
which otherwise obtains when the poison is coarsely sprinkled or too
strong. It also renders the poison more permanent. On the leaves,
especially on the under surfaces, the London purple and flour can be
seen for several weeks after it has been applied, and the insect is not
only destroyed, but is prevented from reappearing, at least for a long-
period. By poisoning again, a few weeks later, the insect is deterred
with greater certainty for the entire season. By being careful to ad:
minister the poison before the insect has worked, and, above all, to
diffuse the spray finely but not in large drops, no harm worth mention-
ing will accrue to the plant from the proportion of poison recommended.
The new growth that developed after the first poisoning was protected
by one-fourth of a pound to the barrel in 1882. From midsummer un-
til autumn the unpoisoned half of the grove remained denuded of foli-
age, while the poisoned half retained its verdure. The little damage
then appearing in the protected part was mostly done before the first

THE IMPORTED ELM LEAF-BEETLE. 1 •"

treatment. Egg* were laid abundantly throughout the season. Many
of these seemed unhealthy and failed to develop, probably because they
were poisoned. Many hatched, but the young larva* soon died. TJje
eggs were seldom deposited on the young leaves that were appearing
after the poison was applied, but were attached to the developed Leaves,
and here the larvae generally got the poison to prevent their attack
upon the aftergrowth. Still the young leaves became perforated to
some extent. The adults, which My from tree to tree, appeared plenti-
ful without much interruption throughout the season, and often several
could be seen feeding on each tree. Possibly many of these may have
become poisoned before depositing the eggs.

The efficiency of London purple being established, it will generally
be preferred to other arsenicals, because of its cheapness, better diffus-
ibility. visibility on the foliage. &C. As the effects of the poisons com-
monly do not appear decidedly for two or three days after their admin-
istration, the importance of the preventive method of poisoning in ad-
vance cannot be too strongly urged. As the effect is slow in appear-
ing, impatient parties will be apt to repoison on the second or third day.
and thus put on enough to hurt the plant when the effect does come.
Much depends on dryness or wetness of the weather, but good effects
may be expected by the third or fourth day.

London purple seems to injure the plant less than Paris green.
Treatment with Paris Green. — In 1883 the Paris green was first applied
on the 29th of May, at which date the eggs were extremely abundant
and hatching rapidh on the leaves. Paris green, flour, and water were
mixed by the means previously employed with London purple and
already described. The mixture was applied to the north part of the
same grove of elms. Thus far experience shows that the Paris green
is effective against the insect, but that this poison injures the plant more
than does the London purple.

Three-fourths of a pound of Paris green to a barrel (36 or 40 gallons
of water, with 3 quarts of flour, may be regarded as a poison mixture
of medium or average strength for treating elms against these beetles,
and the indications thus far are that the amount of Paris green should
not be increased above one pound or be diminished much below one-
half a pound in this mixture. To a bucketful of water three-kmrtli^
an ounce of Paris green may be used. The action of this poison is
slow but severe, and varies much with the weather. Thus far the re-
sults of tests have been varied so much by the weather and different
modes of preparation and application that they will be repeated. When
used strong enough to cauterize the leaves the poisonous action upon
the plant may be observed to continue tor several weeks.

Mechanical Means of Applying the Poison. — When many trees were to
be sprayed a cart or wagon was employed to haul the poison in a large
barrel provided with a Starrer, force-pump, skid. &c. The folio?

16 THE IMPORTED ELM LEAF-BEETLE.

brief account of the skid, mixer, barrel, and pump may be reproduced
here from our last Annual Report :

The skid is a simple frame to hold the horizontal barrel from rolling, and consists
of two pieces (Plate I, Fig. 3 a a) of wood, about the length of the barrel, and in
section about 3 by 4 inches, joined parallel, apart from each other, by two cleats, b b.
The inner upper angles may be cut to match the curve of the barrel, as at cc. The
barcel being placed upon this frame is next to be tilled.

A good device for mixing the poison thoroughly with the water and for idling the
barrel is shown in section in Plate I, Fig. 4. It consist of a large funnel that will
hold a bucketful, and has cylindrical sides, (j g, that rest conformant on the barrel.
In this is a gauze or finely-perforated diaphragm or septum, rf, and a funnel base, t i7
with its spout, j), inserted through the bung.

By reference to Plate I, Fig. 4, the barrel, fc, will be seen in section, and some of
its details, together with those of the pump and stirrer, may be noticed. The ful-
crum, /, has a foot below, screwed to the barrel. Through its top is a pivot, o. on
which tilts the pump-lever, i i, which is similarly hinged at b to the top of the piston-
rod. The pump-cylinder, q, is also hung upon trunnions, i, projecting into eyes. In
this illustration the eyes, e e, have each a neck fitting in a slot cut through the stave
oppositely from the side of the buug-hole, and beneath the stave is a foot on the eye-
piece. Its neck is so short that the eye is held down firmly against the top of the
stave, while the foot is as tight against its under surface. The length of its eye-piece
is a little less than the diameter of the bung-hole, into which it may be inserted to be
driven laterally into the slot. The slot is longer than the eye-piece, so the latter may .
be driven away from the bung-hole for a distance greater than the length of the trun-
nion pivot. Then the pump being iuserted, until these pivots come opposite the eyes,
the latter may be driven back as sockets over the pivots, which play in them when the
pump is worked. To hold these eyes toward the pump and upon the trunnions a
wedge, v, is driven in the slot beyond each eye-piece. Thus the pump is easily at-
tached or removed, and its union with the barrel is strong and firm. Perchance it be
desired that this pump-hole be bunged, the side slots may be wedged to make the
barrel tight.

The parts of the pump being hung as described, the hinge, ft, forms a toggle-joint,
and in its action causes the pump to oscillate on its trunnions, its basal end swinging
wider than its top, as indicated by the dotted line from x to y. Upon the extremity
of this swinging end is a loop, //, through which is passed a stirrer-bar, m n, made to
sweep back and forth in the lower side of the barrel, thus to agitato and mix the sub-
stances considerably during the operation of the pump, every stroke of the handle
causing one or two strokes of the stirrer.*

The method of inserting and extricating the stirrer-bar is as follows : It is raised
with the pump until the end, », comes opposite the bung-hole, through which the
bar may be pulled out by the cord, w, which is attached to the end. n, and also prefer-
ably to the bungs, r and z, as shown. Through the same hole the bar may be inserted.
This stirring device is the simplest in construction and operation of any yet contrived,
while working as it does with reference to the concavity of the barrel it is perfectly
effective.

The pump is double-acting and very powerful, giving strong pressure
to disperse the liquid far and finely, for, with the eddy-chamber nozzle
used, the greater the pressure the finer is the liquid atomized. A block
or other catch may be fixed on the side of the barrel to fit against the
skid and prevent the barrel from rocking therein, as might otherwise
happen, when it is nearly empty, if much power is applied. About one
pailful of poisoned water was sprayed upon each tree. When only two
or three trees were to be treated, an aquapult or other bucket-pump

THE IMPORTED ELM LEAF-BEETLE. 17

was used to force the poison from a bucket carried by hand. The Paris-
green mixture needs to be almost constantly stirred, as this poison pre-
cipitates quickly; but with London purple the agitation is only <
sionally necessary.

Connected with either pump is a long, flexible pipe, with its distal
part stiff, and serving as a long handle whereby to hold its terminal
nozzle beneath the branches or very high up at a comfortable distance
from the person managing it. Parts of one form of this extension pipe
are shown in Figs. 1 and 2.

To the pump-spout is attached the long, 2-ply, flexible hose, h Ji, of
J-inch caliber. Its considerable length, 12 feet or more, allows the
nozzle to be carried about the tree without moving the pump. Beyond
its flexile part the hose, h, passes through a bamboo pole, &, from which
the septa have been burned out by a hot iron rod. At the distal end of
the pole the hose terminates in a nozzle, n or m. When the nozzle is in
its natural position, w, the spray, z, is thrown straight ahead, and this
suits well for spraying very high branches; but for spraying the under
surfaces of the lower parts of the tree it is necessary that the nozzle
discharge laterally from the pipe, and this is accomplished with a noz-
zle having a direct discharge by bending it to one side. The nozzle. «,
and spray, s, are directed laterally, and the nozzle, », is maintained in
this position by a metallic hook or eye, r, having a crooked stem inserted
at the side of the hose in the end of the pole. Where the side spray is
permanently desired, the metallic stem is inserted inside the hose and
connected with the base of the nozzle, or the tubular stem of the nozzle
is given the desired crook. For small trees the simpler exteusion-pipe
shown in Fig. 2 is satisfactory. The metallic tube t, several feet in
length, is used as the stiff part, f, connected with the hose, h. One longer
metallic pipe, having telescopic sections made tight by outside seg-
ments of rubber tubing, has also been employed, and is a very desirable
extension-pipe. Where only low end-spraying is to be done, as upon
small trees, &c, the eddy-chamber nozzle is set upon such a pipe, or
upon its own stem, so as to discharge at right angles therefrom ; but a
diagonal position of the chamber, n, on its stem, t, throws the spray, s,
at an intermediate angle between the right angle and a direct line, by
which, without any readjustment, the spray, s, can be directed high or
lower, beneath the foliage or above. For general use this kind of noz-
zle is the best. With ordinary force-pump pressure the discharge-hole
of the nozzle is about one-sixteeith of an inch in diameter for misty sprays
with particles invisibly small. Bather than use the larger, coarser
sprays, which were usually employed in these tests, it IS better to use
the finest spray. The spray falling upon the extension-pipe soon accu-
mulates enough to flow down the pole and wet the hands. To prevent
this a wrapping washer of leather or other flange may surround the pole
proximally from the spray, and the drip will drop off from its margin.
Such an arrangement is indicated atj in Plate I, Fig, 1.
145G5 Bull. 0 2

18 THE IMPORTED ELM LEAF-BEETLE.

While one person operates the pump, another, standing in the vehicle
or upon the ground, directs the spray by the stiff part of the pipe. Thus
the operator cannot only spray higher and lower with convenience, but
he can, to a great extent, move the spray from place to place without
leaving his own position and without moving the vessel of poison with
the pump.

The hose and bamboo combination was conceived of and used as the
lightest long, stiff tube practicable for these purposes, and it has answered
admirably. A similar pole, with a metallic tube in its interior, with a
nozzle not producing the very fine mist desired, and lacking the side
discharge, &c, was afterward learned of as being used in California.
(See U. S. Agricultural Department Eeport, 1881-,82, p. 208.)

By the apparatus used, when everything is prepared, a tree can be
sprayed quickly, and a large grove is treated in a short time. It is
equally adapted for forestry use in general, and likewise available for
poisoning on fruit trees, when not in fruit, while the shorter style of ex-
tension-pipe is convenient for underspraying all kinds of low plants.

Plate I.

DEVICES FOR UNDER8PRAYING TREES WITH INSECTICIDES.
[From Ann. Kept. U. S. Dept. Agr., 1883.]

Fig. 1. Parts of hose-pole device for spraying trees : Bamboo pole, b b ,• drip-washer,;*,- hose, hx; side

hook, v; eddy-chamber nozzle, n, m ,- spray, z, s.
Fig. 2. Metallic hand-pipe with diagonal nozzle : Hose, h; metallic pipe, t ,■ diagonal eddy-chambernoz-

zle, »,- its removable face, i; spray, s.
Fig. 3. Barrel rest or skid : Two coupling-cleats, bb,- two"side rests, a a ; chamfered concave, c c.
Fig. 4. Stirrer-pump with barrel and mixer-funnel in section .- Funnel, u ,• its cylindrical sides, g g ;

funnel base, t t; spout, p (in bung-hole, k); gauze septum, d ,- barrel, k k; trunnions, i;

trunnion-eyes, e ,• wedge,?;,- lever-fulcrum, /,- pump-lever, i i ,• swing of the lever-head and

piston-top, a 6 c,- cylinder packing-cap, c ,• cylinder, q ,- its swing, a; y ,• stirrer-loop or eye,

h ; stirrer-bar, m n ; rope, w w ,• bungs, r, z.

20

Bulletin 6, Department of Agriculture, Division of Entomology.

Plate I.

%s

i

Fig. 2.

Figr. 1.

a

Fie. i.

Devices for onderspraying i r