Emulsions of wormseed oil and of carbon disulfide for destroying larvae of the Japanese beetle in the roots of perennial plants

Historic, archived document

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

Washington, D. C. v May, 1925

EMULSIONS OF WORMSEED OIL AND OF CARBON DISULFIDE
FOR DESTROYING LARVAE OF THE JAPANESE BEETLE IN THE
ROOTS OF PERENNIAL PLANTS !

By B. R. Leacu, Associate Entomologist, and J. P. JoHnson, Junior Entomolo-
gist, Fruit Insect Investigations, Bureau of Entomology

CONTENTS

Page Page
‘HedNANTS CONCCIMNCG:: s-—) 3 ea 1 | Carbon-disulphide emulsions__--._.._____-_- 13
Preliminary WOrk.. 202. ee I ee 2 | Toxicity of carbon-disulphide emulsion to
Oil of wormseed (American)_..-__-__-_.-__-- 3 larvee.n- 22 PE Be ee 14
Wormseed-oil emulsions__________---_-___-_- 4 | Application of carbon-disulphide emulsion to
Toxicity of wormseed-oil emulsions_________- 1 lanve and peonies. 2s ei2 tht Pe 15
Application to larve in soil and plants___-___ 9 | Commercial use of emulsions______________—- 15
Value of wormseed oil as an insecticide--____- 12 | Summary and conclusions_______ ________-_ ~~ 16
Treatment of peony roots___._----.-.___---_- 12.|, Literature cited _- . .. <Eeaeeeeeea eee 17

THE PLANTS CONCERNED

Japanese iris (Jris kaempferr),? peonies (Paeona spp.), and per-
ennial phlox (Phlox spp.) are all extensively grown in and near the
area infested by the Japanese beetle, Popilliajaponica Newm. The
acreage of these crops in nurseries growing miscellaneous perennial
stock is considerable, and there are also nurseries of considerable
size specializing in iris and peonies.

These three plant species are essentially different from each other in
root structure. The roots of Japanese iris (fig. 1) are an impene-
trable mass of coarse fibers interspersed with small quantities of
soil and emanating from a hard, thick rootstock or crown. Larve
of the Japanese beetle are found in this mass of roots and soil close
ap to the crown, and can be discovered and removed only by cutting,
which is an obviously impractical method. The roots of perennial
phlox, while coarse and heavy, are not matted to any great extent
except when the soil is wet at the time of digging in November,
but this condition prevails in two out of every three years in New
Jersey and it is then difficult to remove any larve present except
by washing. This operation appreciably injures the roots. In the
case of the peony, the root structure is tuberous with many cavities
mostly formed underground by the flower stems of the previous

1 The writers are indebted for assistance rendered by J. W. Thomson and W. E. Fleming, investigators,
New Jersey State Department of Agriculture. :

2 It is fairly probable that the Japanese beetle entered the United States in the larval form in the roots
of iris from Japan.

31469°—25;,——1

fe BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

year’s growth. These cavities fill up with soil (fig. 2) and fre-
quently afford shelter to larve of the beetle. The larve can be
detected and removed only by cutting, which frequently ruins the
lant.
It has been found impossible to remove all the larve from these
plants by such ordinary expedients as shaking or washing. In 1920
and 1921 only a portion of these crops was marketed, since no method
was known whereby all the larve present in the roots of the plants
could be killed without injury to the plants themselves. Under
these circumstances the writers undertook a study of this problem in
an effort to discover a solution in which the plonts could be dipped

without injury to them for the purpose of killing any larve present
in their roots.

PRELIMINARY WORK

During 1920 and 1921 the writers con-
ducted an extensive series of tests to de-
termine the effect of various compounds
upon the larvee of the Japanese beetle and
upon the roots of plants. The experi-
mental procedure in the case of each
compound was the same; larve were dip-
ped for varying periods of time in filtered
solutions of the compound under investi-
gation and the mortality of the larve de-
termined; potted plants, the soil of which
was infested with larve, were watered with
the filtered solutions and the larval mor-
tality and the effect of the compound upon
the plant were observed.

A partial list of the materials tested in
this connection is givenin Table 1. They
include inorganic salts, alkaloids, essen-
tial oils,and representative compounds of
the various organic groups. It will be ob-
served that oil of wormseed not only con-
trolled the larva but checked the plant
only to a slight extent; carbon disulfide
was somewhat more injurious to the plant.
Fic. 1.—Japanese iris (Iris kaempferi): ‘Lhe other compounds were either innocu-

ese beetle larves intereesey" 72Pan- ous to the larve or killed the plants. In

view of these results and in considera-

tion of the great amount of experimental work required to test

out each compound thoroughly the writers decided to limit the
research to wormseed oil and carbon disulfide.

EMULSIONS FOR JAPANESE BEETLE 83

TABLE 1.—Results obtained from dipping third-instar larve of the Japanese beetle
in various solutions

Larve ! dipped

pe ae
: tion o F
Concentration of ; Effect of solution
Compound solution Suinican Propor- ae on plants 4
dip nee in soil ?
killed

Hours | Per cent | Per cent
Zinceeblonide:- <22 2.222): - 5eper cent 2242 27 2 0 0 | Killed.
Wornreed oil! 8 Saturated __-___._- 6 100 100 | Slight check,
Al pRataptnol 222 ees =e eis dO. 2 cee seas 1 100 75 | Killed.
Boenzaldehyde- = ss. -< ie se |e a OS te ee aN 1 66 0 Do.
Beta-napthol benzoate_______|____- ole eee 272 Oe 1 0 0 | Normal.
Carbon disulfide_____________ 4 saturated_____-_- 1 100 100 | Checked somewhai.
Carbon disulfide_____________ Saturated _________ 4% 100 100 | Checked badly.
Formaldehyde_____________-_- bp percents -2- 5 = 1 100 0| Killed.
rf: a ees ee a) pen cent= fe 1 0 0 Do.
Mercuric chloride____________} 0.1 per cent________ 1 0 0 | Injured badly.
Paraldehydes) £1 Wak i Sper cena Lee 1 0 0 | Killed.
IBETIGiMe= see tr sn. Maes.) 3 per centee 285 1 0 0 Do.
Petroleum ether_____________ Saturated ________- 1 0 0 | Normal.
SE Tiyant Osage sk es Puree se sella Ole Gis Bek see 1 100 90 | Checked considerably.
MolwenG=r7 2 2ieee Se PA Ae By dot falis 1 100 33 | Checked.

1 Larve not in soil.
ty are in pots of soil (ight sandy loam) watered with a volume of the solution equal to the volume of
the soil.
3 Salvia, aster, nasturtium, and chrysanthemum.

OIL OF WORMSEED (AMERICAN)

American wormseed oil (oelum chenopodi anthelmintict) is distilled
in Carroll County, Md., from the entire cultivated plant of Cheno-
podium ambrosioides anthelminticum Linné (family Chenopodiaceae).

In the ninth edition of the U. S. Pharmacopeia the oil of cheno-
podium, or oil of American wormseed, is described as a volatile oil
distilled from the above-named plant. The oil is colorless or pale
yellow, soluble in 8 volumes of 70 per cent alcohol, and varying in
specific gravity from 0.955 to 0.980 at 25°C.

In recent years producers and dealers have urged that the U.S. P.
standards for this oil should be lowered, basing their argument on the
fact that authentic oils obtained at the stills do not come up to the
standard. However, Russell (6)? has shown conclusively that this
shortcoming is due to faulty distillation, and that by distilling the
herb with a large volume of steam during a relatively short period
of time an oil can be produced that will meet all the U.S. P. require-
Seat CHEMICAL COMPOSITION OF THE OIL

American wormseed oil (2) contains minute quantities of the
lower fatty acids, chiefly butyric acid, and less than 0.5 per cent of
methyl salicylate. Of the remainder of the oil at least 60 per cent
is ascaridole, with about 5 per cent of the corresponding glycol and
30 to 40 per cent of a mixture of hydrocarbons made up approximately
of cymene 15 per cent, a-terpinene 5 per cent, and a new laevorota-
tory terpene, 10 per cent.

Practically ¢ pure ascaridole can be separated from oil of worm-
seed by a fairly easy process (4). The oil is fractionated under
vacuum, the heat being kept low, for wormseed oil or, specifically,

3 The figures (italic) in parentheses refer to “‘ Literature cited,’’ p. 17,
4 From correspondence with G. A. Russell,

4 BULLETIN 1332, U. 8. DEPARTMENT OF AGRICULTURE

ascaridole, suffers a molecular rearrangement when heated to 150° C.
Consequently, if a vacuum of not over 6 millimeters is employed and
the heat of the bath regulated the temperature of the oil need never
be brought near 150° C. and the danger of explosion, owing to sudden
molecular rearrangement of ascaridole, is virtually eliminated.
Practically all of the first fraction up to 80° C. will consist of terpenes;
the next fraction, which is ascaridole, boils at about 95° C. at 6
millimeters pressure, and the residue in the distilling flask contains
some resinified products and considerable ascaridole glycol. To
obtain pure ascaridole it is sometimes, in fact almost always, neces-
sary to refractionate the ascaridole fraction. _

The principal constituent of the oil, ascaridole, C,,H,,O,, has a
specific gravity of 1.0024 at 25° C., a disagreeable, benumbing odor,
and a disagreeable taste. Ascaridole (so called because of its action
against Ascaridae) is generally conceded to be the active ingredient
of the oil, although some investigators state that the terpenes and
the residue containing ascaridole glycol are also active. The writers
have done some work on this point, with results reported later in
this bulletin (Table 6).

Inasmuch as ascaridole is essentially the active ingredient of
wormseed oil from the standpoint of toxicity toward insects, it is well
to purchase the oil on the basis of astride content rather than on
that of price. A lot of oil containing 45 per cent of ascaridole at
$2.50 a pound is not as economical of the money invested as another
lot of a containing 65 per cent of ascaridole and priced at $3, since
the concentration of the dip for the control of the Japanese beetle
larva is based on ascaridole and not on wormseed oil.

Under these circumstances it is advisable before buying oil in
uantity to determine the ascaridole content by means of the method
evised by Nelson (5). In a cassia flask, the neck of which holds 10

cubic centimeters, graduated in tenths, agitate thoroughly 10 cubic
centimeters of the wormseed oil to be tested with 60 per cent acetic
acid, made by mixing 60 parts by volume of glacial acetic acid with
40 parts of water. The flask is then filled to the mark with 60 per
cent acetic acid and allowed to settle. The volume of undissolved
oil is deducted from 10; the remainder, multiplied by 10, gives the
volume percentage of ascaridole in the sample.°

Wormseed oil is but very slightly soluble in water, and for that
reason an aqueous solution of it has very little promise as a dip for
the control of the Japanese beetle larva. Under the circumstances,
probably the only practical method of regulating the concentration
of oil in the dip is to make an emulsion of the wormseedoil which,
when added to the water, will disperse evenly.

WORMSEED-OIL EMULSIONS

Since this emulsion must be one that will disperse in water, it
follows that water must be the external phase and wormseed oil the

5G. A. Russell, in a letter to the writers, makes the following observations on this method of ascaridole

assay: ‘‘This method is only approximate, but no other method is known. The 60 per cent acetic acid
takes into solution any ascaridole glycol present in the oil, and thus the apparent percentage of ascaridole
is increased. In well-prepared oils which are comparatively fresh the asearidoie*glycol is present only in
small amounts, so that including this in the determination of ascaridole means that only a small error is
introduced, amounting to probably 4 or 5 per cent. I found that in order to get good results with this
method the acetic acid solution must be made up fresh, using glacial acetic acid which has not stood in

partly-filled containers for any length of time. That is the acetic acid should be fresh,”

= ae

EMULSIONS FOR JAPANESE BEETLE 5

internal phase. Various hydrophile colloids such as soap, glue, gum
arabic, etc., were tested in this connection as emulsifiers. In each
ease the colloid was dissolved in hot water, added to the wormseed
oil, and shaken until the emulsion formed. In this manner 15 cubic
centimeters of a 20 per cent gum arabic solution added to 10 cubic
centimeters of oil gives a stable emulsion; 20 cubic centimeters of
0.5 per cent agar-agar and 5 cubic centimeters of oil produced a
stable emulsion; 10 cubic centimeters of a 2 per cent glue solution
added to 5 cubic centimeters of oil proved to be a very stable emulsion.
Dextrin, saponin, and starch were found of little value in this con-
nection.

While the results with miscellaneous colloidal emulsifiers as
described above were satisfactory, the major part of the work was
done with soap as the emulsifier, since this colloid appeared the most
satisfactory of all. A commercial brand of caustic potash fish-oil
soap diluted with water was mixed with the oil in varying proportions
and shaken. In the majority of cases no emulsification occurred.
Another procedure was then undertaken; the undiluted soap was
first ae very thoroughly with the oi!, giving a so-called ‘ miscible
oil” which when mixed with water gave a perfect emulsion in the
instances where sufficient soap was present. The length of time
required for emulsification varied directly with the concentration of

the soap.
STABILITY OF THE EMULSIONS

Emulsions were obtained with 20 cubic centimeters of oil and
amounts of soap varying from 10 cubic centimeters down to 0.5
cubic centimeter. A mixture of 0.25 cubic centimeter of soap to
20 cubic centimeters of oil failed to produce an emulsion, probably
owing to the fact that not sufficient soap was present to form a film
at the oil-water interface.

The question therefore arose as to the optimum amount of soap.
It was thought that within certain limits the greater the amount of
soap present the more thorough would be the division and the smaller
the size of the oil globules; in other words, the finer the water suspen-
sions and the more stable the emulsion the greater would be the
number of oil globules, the greater the surface of the oil-water inter-
face, and, therefore, the greater the amount of soap necessary. If
this hypothesis is accepted it must be assumed that there would be
either an increase in the size of the oil globule with the decreased
amount of soap or a diminution in the thickness of the soap film on
the surface of the globule. Upon measurement it was found that
there was an actual increase in the size of the globule, thus explaining
the decreased stability of the emulsion with the decreased amount
of soap. The measurements are given in Table 2.

TABLE 2.—Stability of wormseed-oil emulsions prepared with potash fish-oil soap

Ingredients of emulsion
Emulsion number Bars cP OP ata ribo s al Size of globules Remarks
Soap Oil Water

Pao Cue: Gc: Microns
20 10 | 1 to 12_____________] Stable; best emulsion.

5 1
20 qn Glugiaoee oe Ae Unstable.

L 5 20 KO) | cs ce 0 a ae ee Unstable.

, 25 20 TEA) [2S See ge Sea Did not emulsify.

6 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

From these measurements it is apparent that there is an optimum
proportion of soap above which there is on standing a marked sepa-
ration of the soap from the emulsion and below which there is a tend-
ency for the globules to increase in size to such an extent that the
mixture either fails to emulsify or easily breaks after emulsification.

Soaps vary greatly in emulsifying power, some brands being use-
less and, in fact, two batches of the same brand may vary greatly in
emulsifying power (7). Under these circumstances the writers found
it necessary to test each purchase of soap before emulsifying any
quantity of wormseed oil for experimental purposes. In practice,
in the hands of the novice, any deficiency in the soap used might
easily result in an unstable emulsion. ‘The writers therefore made a
series of tests to determine the possibility of preparing wormseed-oil
emulsion by means of such standard materials as oleic acid and
sodium or potassium hydroxide, according to the equation—

C.H,, CH:CH(CH,), COOH + NaOH =H,0+ C,H,,CH:CH
(CH,),COONa.

In making these emulsions the oleic acid was added to the oil and
shaken, then N/10 NaOH or N/10 KOH was added. The mixture
emulsified immediately. The various tests are compared in Table 3.7

In using these emulsions in practice it seems advisable either to
use the oleic acid or, if a commercial brand of soap is employed, to
be absolutely sure by test that the material will produce a stable
emulsion.

TABLE 3.—Preparation of wormseed-oil emulsions with oleic acid and an hydroxide

Quantities of—

HIMUISION NUMPCL. |\iaegise a, eee an Remarks on emulsions formed

Oil Acid
Ce: Cle C.c

LS) ee oes eee Peer cae 20 0.12 3.76 | Oil separated out in 1 hour.

ere 20 0. 24 7. 56 | Oil separated out in 1 hour.

O15 Ao) eet Re ey sere toe 20 0. 40 12.60 | Stable emulsion. Best of series.

ASS SST Se 20 0. 80 25. 20 | Stable emulsion.

Lgl. ee Z 20 1. 20 37.80 | Stable emulsion.

7, Ss SP 2 eee ae a 20 1. 60 50.40 | Curdy emulsion. Too much emulsifier.

7( LAS ete ea a arn Sree 20 2. 00 63.00 | Curdy emulsion. Too much emulsifier.

Quantities of—

Emulsion WA PRETI TT Oma a aA Remarks on emulsions formed
| Oil | Acid
EY ha eae Se Se 20 0. 20 6.30 | Oil separated out.
Ase Sey prs 20 0. 40 12.60 | Stable emulsion. Best of series.
108A? SS Me abet) 20 0. 60 18.90 | Stable emulsion.
Sipe Se ee er: 20 0. 80 25. 20 | Stable emulsion.
“2 aR FOE 20 | 1. 00 31.50 | Stable emulsion.

® The molecular weight of oleic acid is 282.37 and its specific gravity is 0.89; it follows that 317.3 cubic centi-
meters of the acid will make a normal solution. Therefore 317.3 cubic centimeters of oleic acid is neutrali-
zable by 1,000 cubic centimeters of normal sodium hydroxide, or 0.03173 cubic centimeter of oleic acid by 1
cubic centimeter N/10 sodium hydroxide. Conversely, 1 cubie centimeter of oleic acid is neutralizable by
31.5 cubic centimeters of N/10 NaOH.

7 The writers have been guided in the preparation of these emulsions by Clayton (1).

EMULSIONS FOR JAPANESE BEETLE a
TOXICITY OF WORMSEED-OIL EMULSIONS

The dip made with emulsion of oil of wormseed was tested in three
different ways: (1) Larve, free from soil, were submerged in the dip
for varying periods to determine the time necessary to kill them at
various temperatures. (2) A similar series of exposures was made with
larve embedded in soil. (3) Plants infested with the larve were
immersed in the dip under varied conditions of temperature and
length of exposure to determine the toxicity of the material to the
larvee under natural conditions and the resistance of the plants to the
insecticide. The entire crop of one of the local nurseries was treated
in this test, which was carried out under commercial conditions.

TOXICITY OF WORMSEED OIL TO JAPANESE BEETLE LARV/®

The toxicity of the emulsions of wormseed oil to the larve of the
J age beetle was determined by submerging the larve, free from
soil, in the dip for varying periods of time at various temperatures.
Emulsion 1 as listed in Table 2, and emulsions 3A and 9A of Table 3,
were employed in these tests in the proportions of 1 cubic centimeter
of ascaridole to 6 liters of water. The wormseed oil employed assayed
75 per cent ascaridole by the acetic acid method already described.
The results of these tests are presented in Table 4. It will be ob-
served that the best results were obtained when the temperature of
the dip was maintained at 65° or 70° F. Lower temperatures reduced
the toxicity of the material.

TABLE 4.—Tovzicity of wormseed-oil emulsions to Japanese beetle larve (not in soil)!

Percentage of larvee killed by immersion in dip for hours specified

Temperature
of dip
3 4 5 6 7 8 9 12 15 18 21 24
OOH. 26:
50 TUR (Rte td ght ps) 8 SS) Re ES 0) gaat ese ae Be Soe 75 75 75 100 100 100
60 16 0 aia ee beeen aa 79S Fee cree |S ae eta 100 100 100 100 100 100
65 18 25 50 25 100 100 100 100 100 TOO 236 SLs Re ee See
70 21 0 50 75 100 100 100 100 LOO | ars a |e w Bhawani tia 2) oy Sg

1 A total of 500 larvae were used in the tests on which this table is based. In each instance here recorded
the larvee were immersed for the specific time, and the percentage of those killed is tabulated. In each
case the dip contained ascaridole in the proportion of 1 cubic centimeter to 6 liters of water.

TOXIC STABILITY OF WORMSEED-OIL EMULSION

In the course of the experimental work several samples of the
emulsion of various ages accumulated. ‘These were tested under
identical conditions and all on the same day in order to determine
whether the stock emulsion on standing had undergone any change
which might affect its toxicity. The results of these tests are given
in Table 5. It will be observed that the emulsion did not decrease
in toxicity within the space of 40 days. The results indicate that the
toxicity will persist indefinitely if the emulsion is kept in a cool
place, since the chemical change, if any, is slow.

8 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

Taste 5.—Comparative toxicity of stock wormseed-oil emulsions of various ages }

Percentage of larve killed by immersion in dip for

hours specified
Age of stock emulsions in days :
5 6 7 8 9 10 15
ee. Oe Pei FAL TOE US TED Ee EEE 50 100 100 100 100 100 100
re a Win ee ee Oe 75 100 100 100 100 100 100
1 Nk nll nme a cP A Sgt 100 100 100 100 100 100 100
Dea ae sd ee Tey eet) Ey cee ee ee oe 100 100 100 100 100 100 100
31 | raise ee Ree SCE eS 2 ee RS ee 75 100 100 100 100 100 100
Bhp 2 8 220s oe ci Sa ee cee Se 75 100 100 100 100 100 100

1 All the emulsions subjected to this test contained 1 cubic centimeter of ascaridole to 6 liters of water.
The test was applied at a uniform temperature of 70° F. (21° C.). A total of about 800 larve were used
in the tests on which this table is based.

COMPARATIVE TOXICITY OF THE INDIVIDUAL INGREDIENTS OF WORMSEED OIL

As already stated, wormseed oil when distilled under a vacuum
of approximately 6 millimeters pressure can be separated by proper
technique and control of temperature into three fractions consisting
mainly of (1) terpenes, (2) ascaridole, and (3) a residue containing

rincipally ascaridole glycol. However, in separating the oil into

ates for determining the toxicity of its several constituents,
four fractions were made, of which the first consisted maimly of
terpenes, the second of a mixture of terpenes and ascaridole, of
which the terpenes constitute the major portion, the third of prac-
tically pure ascaridole, and the fourth a residue consisting ae
pally of ascaridole glycol. Data on the relative toxicity of these
ingredients are presented in Table 6.°

In making up the individual @&ps for the tests, material from each
fraction was emulsified with soap, using 10 cubic centimeters of
soap, 10 cubic centimeters of water, and 20 cubic centimeters of the
material, as was done with the wormseed oil in making the first
and most satisfactory emulsion in testing the stability of emulsions,
as recorded in Table 2. For each test to 6 liters of water was added
3.67 cubic centimeters of the emulsion. It will be noticed that all
the ingredients of the oil are toxic to the larve. The ascaridole was
completely fatal to larve in 5 hours, the terpenes in 8 hours, and
the residue in 12 hours. The results merely emphasize the fact
already stated that in buying oil of wormseed it is advisable to
purchase primarily on the basis of ascaridole content rather than on
that of price.

§ With respect to the ascaridole glycol of the fourth fraction, the following excerpt from a letter from
G. A. Russell, by whom it was fractionated and assayed, may be of interest: ‘‘I have never done any work
on the keeping qualities of wormseed oil, but Nelson examined five samples of American oil which had
been shipped to Brazil and subsequently returned to the United States, all of which were at least 1 year
old. He found that the distillate residues, while higher than those found in fresh oil, were not excessive,
and concluded from this that the oil does not deteriorate very rapidly with age. It is my opinion that oil
preserved in well-filled containers will keep without appreciable change for a period of at least 1 year.
This glycol is formed by the rearrangement of the ascaridole molecules, and apparently is produced by the
action of the steam on the ascaridole at the time of distillation. This may account for the high percentages
of aeigies eg when fractionating oils distilled by means of low-pressure steam over a relatively long
period of time.”

EMULSIONS FOR JAPANESE BEETLE 9

TABLE 6.—Comparative toxicity of four fractions of wormseed oil 1 }

, Percentage of larve
Properties at 25° C. killed by immersion in
dip for hours specified

Fraction F
a Sacitio | ai) polaicon ae
pecific | ¢ in 70 per
gravity @) ™%) ane per cont Bal Gilet <1. 8 | deal ee
3 aleohol | "7°
acid
Per cent
ob xs] AR ie NE i by Es ee ' 0.858 |—Strong.| 1.4805 | None____- 8 50 | 75 | 25 |100 |100 | 100
SOGOU Glee eg rs See ee 0. 950 —8. 73° | 1.4760 | 6.5 vols____ 62.5 |100 |100 | 75 |100 |100 | 100
Third (ascaridole frac-
RIOT) 2B SE We 2 1. 0024 —2.41° | 1.4720 | 1.4 vols___- 100 100 {100 {100 |100 |100 | 100
Fourth (residue)_-._--___--- 1. 0181 —— Dodo |) 1.4400 || O-0,VOloa = 97 75 |100 | 75 | 75 100 100

1 Temperature of dip in each case, 70° F. (21° C.). The larve were immersed for the specified number
of hours in the dip prepared from the fraction tested, and the percentage of those killed is tabulated. A
total of about 300 larve were used in these tests.

L]

APPLICATION TO LARVZ IN SOIL AND PLANTS

The results given in Table 4 indicate the action of wormseed-oil
emulsion dip upon the larve when the latter are removed from their
habitat (the soil) and dipped. The larve are killed in six hours at a
temperature of 70° F. When, however, the soil containing larve or
infested plants (such as iris or phlox) is dipped in the material, it
must be submerged for a longer period in order to kill all the larve
present. The soil itself apparently absorbs the toxic material from
the dip and interferes to some extent with the insecticidal action of
the material upon the larve. This phenomenon of soil absorption
and its relations to the use of soil insecticides has been discussed at
considerable length in a previous paper by Leach and Thomson (3,
p. 68), and summarized as follows:

Dipping tests indicate that certain compounds in solution, capable of produc-
ing a gas insoluble or only slightly soluble in water, are toxic to Popillia larvae.
These compounds may be divided into two classes: (1). Compounds slightly
soluble in water, e. g., carbon disulphide, thymol, mustard oil, ete. (2). com-
pounds readily soluble in water, such as sodium sulphocarbonate and sodium
ethyl xanthate. These compounds in solution, on being decomposed by organic
acids, yield carbon disulphide, the active killing agent.

Saturated solutions of compounds in class 1 (about 1 to 1,000) readily kill
Popillia larvae when the latter are removed from the soil and dipped in the
solution for a definite period of time. However, when Popillia larvae are
embedded in a soil-ball and the latter dipped in these solutions the grubs con-
tained within the soil-ball remain unharmed. Soil adsorption, or, in other words,
physical ‘‘locking up”’ of the compound in solution by the moisture film surround-
ing the minute soil particles, is the apparent reason for the failure of these relatively
dilute solutions to function in soil. That portion of the compound adsorbed by
the soil is apparently rendered impotent as far as its ability to produce larval
mortality in the soil is concerned.

Compounds of class 2, when used in dilute solutions give results comparable to
those obtained by the use of compounds in class 1. However, when compounds
of class 2 are employed in relatively concentrated solutions, a.quantity of the
compound sufficient to produce 100 per cent mortality of Popillia larvae remains
free in the soil after the soil particles have adsorbed the compound to the limit
of their capacity.

However, in the treatment of such plants as Japanese iris, phlox,
and sedum, the limitation above noted does not preclude success 1n
killing the larve present in the root mass, for, while some soil is

31469°—25|——2

10 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

present, it is confined to small amounts which can not be shaken out
or otherwise removed before treatment. The presence of this small
quantity of soil simply slows down the action of the wormseed-oil

emulsion dip and necessitates a longer period of dipping to secure

mortality of the larve under these conditions than is the case when
the latter are entirely free from soil.

TaBLe 7.—Resulis obtained in dipping Popillia larve (in soil balls) in wormseed-oil
emulsion dip }

Percentage of larve killed by immersion
in dip for hours specified

Dosage (ascaridole per 6 liters of water)

6 12 15 18 24
ATCT DIG CON LIN CLO = feo ae ie ee Ue Se Ty Be ree de oe 50 100 100 100 100

PARO ICL ELC CRITE RIALTO URIS canoe eae en ee eee ee ne ae | 75 100 100 100 100

1 The larve were immersed for the specified time at a temperature of 70° F. (21° C.), and the percentage
of those killed is tabulated. A total of about 250 larvee were used in the tests on which this table is based.

The results of dipping soil containing larve are presented in Table
7. The method adopted in this phase of the work was as follows: °
Fifty iris plants were thoroughly shaken and the soil thus removed
discarded. The plants were then cut to pieces and every vestige of
soilremoved and saved. This was measured by volume and averaged
7 cubic centimeters per plant. Ten cubic centimeters of soil con-
taining a Popillia larva was wrapped in a small bag of muslin and the
bag tied at the throat with twine. A sufficient number of such bags,
each containing one larva, were used for the dipping tests the results
of which are presented in Table 7. It will be noted that the 1 cubic
centimeter ascaridole dosage was completely effective in 12 hours,
while twice this concentration did not decrease the period of dipping
necessary to secure a complete mortality. On the other hand, only
six hours of dipping are required for killing the larvee when no soil is
present. This difference of six hours in the period of submergence
necessary to kill the larve when soil is present is due to the partial
soil absorption and consequent slowing up of the action of the toxic
material. Were large quantities of soil present not all the larvee
could be killed even with long-sustained dipping. In practice, there-
fore, the large clumps of iris are broken up into several smaller ones
and the greater bulk of the soil removed by thorough shaking.

During much of the fall and spring shipping seasons for iris, phlox,
etc., the ground is cold. The question arose as to whether larvee in
this cold soil, when dipped, would be resistant to the insecticide. As
a result of a series of experiments on this point, it was found that no
difference in anything but the rapidity of killing resulted, whether the
soil and larvee were warm or cold before or after being dipped, pro-
vided the temperature of the dip itself was not lowered while the
larvee were submerged. However, the immersion of large quantities
of cold soil or plants in the dip appreciably lowers its temperature
and thereby reduces its toxicity. For this reason it is advisable to

* The infestation of iris, phlox, sedum, ete., by Popillia japonica in the infested area at the present time is
light, not more than 5 to 10 per cent of the plants being infested. Further, these plants are expensive.
These two facts render it almost impossible to obtain the preliminary data by natural means, since the pro-
cedure would involve the use and destruction (by cutting) of thousands of plants. The method here
described was therefore adopted and the results checked and confirmed by the dipping of several thousand
plants and their examination to determine the effect of the toxic material upon the larve present,

a a ~~~ ee.

EMULSIONS FOR JAPANESE BEETLE 11

warm the plants in a room at 70° F. for 48 hours before dipping, and
to keep the plants at 70° F. for 48 hours after removal from the dip, in
order to promote the larval mortality.

TREATMENT OF JAPANESE IRIS

The roots of Japanese iris (/ris kaempferi) are mainly dug in the
fall, beginning in September, and shipped immediately for planting.
In September tests were made of the susceptibility of these plants to
the wormseed-oil emulsion. ‘Twelve plants were immersed for periods
of 6, 12, 15, 18, and 24 hours, respectively, in a dip containing 1 cubic
centimeter of ascaridole per 6 liters of water, at a temperature of 70°
F. (21° C.), and the treated plants heeled in or platted in the nursery
for further observation. Similar tests were made at the same tem-
perature and for the same periods of immersion, but in a dip of twice
the strength, i. e., 2 cubic centimeters of ascaridole to 6 liters of water,
with the same subsequent treatment. Without exception, the plants
came through the tests unhurt, and began to throw out new roots and
leaf growth within a few days. The plants apparently withstand
nearly twice the period of immersion in twice the concentration of
dip necessary to insure mortality of the larvee present in the roots.

TREATMENT OF PERENNIAL PHLOX

In this section plants of perennial phlox are dug in the fall, some
when in full bloom to fill early orders, and the remainder from that
time on until the ground freezes. Care is taken in digging to secure
as much of the root system as possible, since the long roots are severed
about 3 inches from the stock, cut into 1%4-imch pieces, and the
pieces sown in coldframes. These root cuttings begin to grow early
in the following spring, and are later set out in the field to produce
the year’s crop. The mature plants, having been trimmed in the
manner described, are packed in damp moss and placed in cold storage
at 32° F. until February or early March, when they are removed,
poibed, and placed in the greenhouse and forced slightly for the spring
trade.

It is evident that an insecticide employed to kill any larve present
in or among the roots of this plant must be absolutely nontoxic to the
roots, stock, and buds. Tests with wormseed-oil emulsion dip for the
control of the larvee in phlox roots were accordingly made at all stages
of the harvesting and storage season. ‘The results, the plants in every
case being unhurt, indicate that wormseed-oil emulsion is a safe
material to use as a means of killing any larve present in phlox
during the period of harvesting and storing it.

Plants were dug when in full bloom, and separate lots, each of
12 plants, immediately dipped, all at a temperature of 70° F., but
each lot for a specified time and in a dip of specified strength. Four
lots were dipped for periods of 6, 7, 8, and 9 hours, respectively, in a
dip contaiming 1 cubic centimeter of ascaridole to 6 liters of waters,
and three lots for periods of 6, 7, and 8 hours, respectively, in a dip
containing twice the proportion of ascaridole. 1 of these plants
came through the treatment unhurt. Immediately after dipping
they were set out in the nursery out of doors, and made a normal
growth during the subsequent spring and summer, the blooms on the
treated plants having in many cases a diameter of 6 to 8 inches.

12 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

Three similar lots, each of 12 plants, were dug after the first heavy
frost and immersed for periods of 6, 9, and 12 hours, respectively,
in a dip eae’ 1 cubic centimeter of ascaridole to 6 liters of
water. The roots had not abla rect che 7 are but, after dip-
ping, the roots were cut off and divided into 1)4-inch pieces and
planted in a coldframe. They developed normally in the spring, but
were somewhat slow in beginning growth. The roots of the plants
of three other similar lots, each of 12 plants, were trimmed and cut
into pieces, after which both plants and root cuttings were immersed
in a dip like that for the other three lots and for the same periods,
respectively. These root cuttings were planted in the same manner
as those of the other three lots and made the same growth in the
spring. The mature plants of all six lots were placed in cold storage
until February 1, when they were potted and pipers in the green-
house, where their growth was equal to that of the controls and in
many cases superior.

Still other plants were removed from cold storage February 1 and
three lots, each of 12 plants, immersed for 6, 9, and 15 hours, respec-
tively, in a dip containing, as before, 1 cubic centimeter of ascaridole
to 6 liters of water. Twenty-four hours after removal from the di
these plants were potted and placed in the greenhouse. Their
growth there was superior to that of the controls.

TREATMENT OF SEDUM SPECTABILE

The showy sedum, Sedum spectabile, has a coarse, matted root
system and is frequently infested with the larve of the Japanese
beetle. To test the efficacy of wormseed oil as a protective dip, four
lots, each of six plants of this species, were dug in the early spring,
the surplus soil adhering to the roots removed by shaking, and the
four lots immersed for 12, 15, 18, and 24 hours, respectively, in a dip
of wormseed-oil emulsion containing 1 cubic centimeter of ascaridole
to 6 liters of water and at a temperature of 70° F. All came through
the treatment without injury to the roots. At the time of dipping,
the plants had made about 3 inches of top growth. This was injured
by the dip and sloughed off, but on potting the plants and placing
them in the greenhouse, the treated plants soon threw out new top
growth and prospered, soon catching up with the controls.

VALUE OF WORMSEED OIL AS AN INSECTICIDE

The results of the experimental work which has been described in
the preceding pages indicate that a dip the insecticidal basis of which
is wormseed-oil emulsion is, under certain conditions, a reliable
destroyer of the larvee of the Japanese beetle, though not rapid in its
action. Of all the compounds tested for this purpose it is the least
toxic to plants. The cost of treatment with this insecticide is not
prohibitive; 1 pound of wormseed oil, assaying 75 per cent ascaridole,
will make 500 gallons of dip. It seems probable that this treatment
could be utilized in many similar cases of needed control of insects.

TREATMENT OF PEONY ROOTS

Figure 2 represents a typical peony root, the root cavity being split
open to show its characteristics as a hiding place for the lates of the
Japanese beetle. In the majority of peony roots the cavities contain
more or less soil, usually compact and in one solid mass; whereas in
iris the soil is interspersed in very small individual amounts through

EMULSIONS FOR JAPANESE BEETLE 13

the tangled root mass, but is appreciable in the aggregate. Experi-
mental work has shown that it 1s much easier to kill the larve in iris
roots than in peony roots because of the difference in the distribution
of the soil. Here, again, soil-absorption is apparently the limiting
factor. A larva in the center of a cubic inch of soil is not affected to
nearly the same extent by the dip as a larva in the center of a mass of
soil and roots consisting of 1 cubic inch of soil mixed with 3 cubic
inches of roots, when both are submerged in the same concentration of
dip. In fact, the submergence of iris roots for 15 hours in a dip con-
taining 0.5 cubic contimeter of ascaridole per 3 liters of water at 70° F.
completely killed the larve in them; whereas twice this dosage was
required for killing the larve in peony roots under the same conditions
of time and temperature. Incidentally the peonies were not injured
by a dip of this greater
strength when submerged
for the time stated, but the
added cost of the dip, while
not prohibitive, led the
writers to experiment with
other toxic materials in
emulsion as a control for
the larve infesting this
particular plant. Of the
materials tested in this con-
nection carbon disulphide
was found to be the most
feasible.

CARBON-DISULFIDE
EMULSIONS

EMULSION 1

Experimental work
showed that carbon disul-
fide could be emulsified by
soaps in general, and the
writers found the old style
rosin-fishoil soap to be the
best for this purpose. It
is a thick, heavy soap and
must be heated with water to dissolve it. When it is availaple a
stock soap solution can be made by adding 12.5 grams of rosin-fishoil
soap to 87.5 cubic centimeters of water, heating until dissolved and
allowing the solution to cool. Add 20 cubic centimeters of this stock
solution to 50 cubic centimeters of carbon disulfide in an Erlenmeyer
flask and agitate until the ingredients emulsify, which will require
but a few minutes. Larger quantities, using the same proportions,
may be emulsified with a butter churn or ice-cream freezer. The
emulsion proper is white and has the consistency of thick cream.
When added to water it disperses evenly and remains indefinitely in
suspension.

Fic. 2—Peony root, divided longitudinally, showing infesta-
tion by larvee of the Japanese beetle

EMULSION 2

Where the old style rosin-fishoil soap is not available a good
emulsion may be made by mixing 0.5 cubic centimeter of oleic acid

14 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

with 20 cubic centimeters of carbon disulfide and adding N/10
KOH or N/10 NaOH until the solution is about neutral to phenol-
phthalein, 10 cubic centimeters of the hydroxide being ordinarily
required.

iviedresically about 18.3 cubic centimeters of N/10 potassium or
sodium hydroxide is required to neutralize 0.5 cubic centimeter of
oleic acid, but in tests by mixing the acid with carbon disulfide it
was found that only 10 cubic centimeters of N/10 hydroxide was
required. This may be due to the solvent action of the carbon
disulfide upon the oleic acid, thus limiting the necessary neutralizing
action of the potassium hydroxide on the oleic acid at the surface of
the carbon disulphide globules, the acid in solution in the interior of
each individual globule probably not being acted upon. The neces-
sity for less than the theoretically correct amount would naturally
result from this condition.

In the case of both of these carbon-disulfide emulsions water is
the external phase and carbon disulfide the internal phase, with a
hydrophile colloid as the emulsifier.

cae Sere emulsion was tested along three lines: (1) Larve
(not in soil) were submerged in the dip for various periods, to deter-
mine the time necessary at various temperatures for the dip to be
completely effective. (2) Peony roots infested with larve were
dipped for various periods to determine the toxicity of the material
to the larve under natural conditions and the resistance of the plant
to the insecticide. (3) The method was tested out under commercial
conditions involving the treatment of the entire crop of one of the
local nurseries.

TOXICITY OF CARBON-DISULFIDE EMULSION TO LARVZ

Larve free from soil were dipped in dilutions of the carbon-
disulfide emulsion at different temperatures and for different
periods of treatment and the results noted. Two dips were used, one
of 4.2 cubic centimeters of emulsion 1, and the other of 4.57 cubic
centimeters of emulsion 2, each to 6 liters of water. The results for
the two were not separately recorded, the preference being slight.
The results in larve killed for different temperatures and periods of
exposure are presented in Table 8. It is evident that the optimum
temperature lies between 60° and 70° F., the latter being preferable,
and that much of the effectiveness of the dip depends upon a tempera-
ture not too low.

TaBLE 8.—Tovicity of carbon-disulfide emulsion to larve of the Japanese beetle
(not in soil)!

Percentage of larvee killed py immersion in dip for hours specified
Temperature of dip (° F.)

' The larvee were immersed for the specified time, and the percentages of those killed are tabulated. A
total of about 400 larve were used in these tests.

EMULSIONS FOR JAPANESE BEETLE 15

APPLICATION OF CARBON-DISULFIDE EMULSION TO LARVZ AND
PEONIES

Larve were placed in the cavities of the peony roots and the
cavities then filled and plugged with soil. The plants thus arti-
ficially infested were dipped in various dilutions of the carbon-
disulfide emulsion for various periods of time but always at a
temperature of 70° F. Forty-eight hours after removal from the dip
the larve were taken from the root cavities and the mortality deter-
mined; the plants themselves were set out in the nursery row and
kept under observation for possible injury to the buds and rootstocks.
This test is of interest in connection with the treatment of plants for
the fall and spring shipping seasons.

Three series of treatments were tried, each series with a particular
strength of solution and varying periods of time. For the first, a dip of
4.2 cubic centimeters of emulsion 1, and one of 4.5 cubic centimeters
of emulsion 2, to 6 liters of water, the two considered as of equal
strength, were used, and peony roots infested as just described im-
mersed in one or the other solution for 6, 9, 12, 15, 18, and 24 hours,
respectively. Plants containing in all four larve were submerged
for each of the periods named. The peonies were uninjured by the
treatment except that the bud scales were blackened by the 24-hour
exposure. All the larve exposed for 12 to 24 hours, inclusive, were
killed; for each of the other two treatments but one larva was killed,
_ the other three coming out alive.

Dips were tried of twice the strength, 8.4 cubic centimeters of
emulsion 1 and 9.14 cubic centimeters of emulsion 2, each to 6 liters
of water, with immersions of 6, 12, 18, and 24 hours, respectively,
four larve with the plants containing them being used in each case.
All the larvze were killed. The peonies were badly checked by the
shortest exposure and killed by all the others.

The strength of dip was again doubled, 16.8 cubic centimeters
of emulsion 1 and 18.28 cubic centimeters of emulsion 2, each to 6
liters of water being used. Four larve, with the plants containing
them, were immersed as before for the several periods of 6, 12, 18,
and 24 hours. In all cases plants and larve were killed.

COMMERCIAL USE OF EMULSIONS

In treating peony, iris, phlox, and sedum plants infested with
Popillia larve the writers have found it best to pack the plants in
tubs until nearly level with the Lop: Galvanized-iron.tubs are best
for this purpose since they rarely leak, as is the case with wooden
tubs, ae they do not absorb the toxic material from the dip.

In cold weather the plants should be allowed to warm up for 24
hours in a room kept at a temperature of 70° F. before being dipped,
and the actual dipping should be performed in a room maintained .
at this temperature.

The water for the dip should be brought to a temperature of 75° F.
In our experience, extra tubs are best for this purpose. When the
water is heated to 75° F., stir in the required amount of emulsion
and pour the mixture into the tubs containing the plants, being sure
that all the plants are submerged.

The dosage and period of submergence for the various plants are
as follows:

Japanese iris.—Dosage, 1 cubic centimeter ascaridole to 6 liters
of water. Allow plants to remain submerged for 15 hours.

16 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE

Perennial phloz.—Same dosage as for iris. Keep in the dip for
from 9 to 18 hours, depending on the amount of soil present on the
lants. :
2 Sedum.—Same dosage as for iris. Dip for a period of from 15 to
18 hours. ,

Peony.—Dosage, 0.5 cubic centimeter carbon disulfide per liter
of water. Dip for a period of 15 hours.

Care should be taken that the temperature of the dip does not fall
below 65° F. at any time during the treatment. At the end of the
period of submergence the plants should be removed from the dip,
the latter discarded, and the plants, after draiming, kept for 48 hours
in a room at 70° F. Care must be taken that the plants do not dry
out before or after the dipping. Plants so treated are then ready
for shipment outside the quarantined area‘ and not before. Any
chilling subsequent to the treatment should be carefully avoided, as
it may lengthen the time required to kill all the larve.

COMMERCIAL EXPERIENCE WiTH THE METHODS

During 1922 and 1923 the writers treated by the above methods
approximately 10,000 Japanese iris, 10,000 perennial phlox, 1,000
sedum, and 15,000 peony, valued in all at $10,000. There have
been to date no complaints from the quarantine officials or con-

signees.
SUMMARY AND CONCLUSIONS

Plants of the nature of Japanese iris, phlox, sedum, etc., have
a matted root system, while peonies are hollow-rooted. It is impos-
sible to eliminate larve of the Japanese beetle which may be present
in these roots by such means as removal of the dirt, by washing or
by other ordinary methods. The experimental work here outlined
was therefore conducted for the purpose of evolving a chemical dip
in which such plants could be immersed for definite periods of time,
to make sure of killing any larvee present, and with no resulting injury
to the plant.

The results of the work indicate that oil of wormseed (American)
and carbon disulfide are the best materials to use for this purpose.
These substances, when added to a hydrophile colloid and water,
are both capable of forming stable emulsions the toxic principle of
which is retained indefinitely.

Oil of wormseed (American).—The primarily active ingredient of
oil of wormseed is ascaridole, (C,.H,.6,). Other ingredients of the
oil are also toxic in varying degrees. For greater certainty the con-
centration of the dip is figured in terms of ascaridole rather than in
terms of wormseed oil.

When Japanese beetle larye, with no soil present, are immersed
for six hours in a wormseed-oil dip the concentration of which is
equal to 0.5 cubic centimeter of ascaridole to 3 liters of water, the
larve are killed, provided the temperature of the dip is maintained
between 65° and 70° F. The experimental results clearly indicate
that the temperature of the dip is the limiting factor in the success
of this method, and under no circumstances must it be allowed to
fall below 65° F. during the course of the treatment. It is advisable
to maintain it at 70° F. |

10 No injury has occurred as a result of the wetting received by the plants. In two series of experiments,

plants were taken out of the dip and immediately packed in damp moss. One lot was placed in cold storage
for two months and the other next to a hot stove for several weeks. The first lot was normal when removed

from storage, whereas the second lot made 6 inches growth in the moss,

EMULSIONS FOR JAPANESE BEETLE 17

When plants infested with larve are immersed in the wormseed-
oil dip, it has been found that longer periods of submergence are
required to insure complete larval mortality. This is due to the fact
that the soil present in the roots absorbs to a certain extent the toxic
material, thereby slowing up its action upon the larve. As a result
of the research here described it is recommended that Japanese iris
and sedum be immersed for 15 hours, and perennial phlox for from
9 to 18 hours, the time depending on the amount of soil present in
the roots. These periods of dipping provide ample margins of safety
over the time actually required to obtain mortality of the larve
under these conditions, while the plants concerned are unaffected by
the treatment.

Carbon disulfide.—tin the case of peony roots it has been found
advisable from the standpoint of cost to use a carbon disulfide
emulsion dip. The plants should be immersed for a period of 15
hours in a dip the concentration of which is equal to 0.5 cubic centi-
meter of carbon disulfide (emulsified) to 1 liter of water. The
same limitations of temperature apply in the use of this material
as in the case of the oil of wormseed.

Commercial experience with these emulsions in 1922 and 1923,
involving the treatment of 45,000 plants of this nature, valued at
$10,000, indicate that when applhed under Government supervision
the method is satisfactory to the quarantine officials and to the
nurserymen from the standpoint of cost and the safety of the plants.

LITERATURE CITED
(1) CLayton, W.
-1923. The theory of emulsions and emulsification. London. 160 pp.
(2) Henry, T. A., and Pacer, H.
1921. Chenopodium oil. Jn Jour. Chem. Soc. (London), vol. 119. pp.
1714-1724.
(3) Leacu, B. R., and THomson, J. W.
1921. Experiments in the treatment of balled earth about the roots of
coniferous plants for the control of Japanese beetle larve. In Soil Sci.,
vol. 12, pp. 43-61.
(4) Neuson, E. K.
1920. The composition of oil of chenopodium ‘from various sources. Jn
Jour. Amer. Chem. Soe., vol. 42, pp. 1204-1208.

(5)
1921. A rapid assay method for the determination of ascaridole in oil of
chenopodium. Jn Jour. Amer. Pharm. Assoc., vol. 10, pp. 8386-837.
(6) RussELL, G. A.
1922. The influence of methods of distillation on the commercial value of
oil of American wormseed. Jn Jour. Amer. Pharm. Assoc., vol. 11, pp.
255-262.
(7) THomas, A. W.
1920. A review of the literature of emulsions. Jn Jour. Indus. and Engin.
Chem., vol. 12, pp. 177-181.

ORGANIZATION OF THE
UNITED STATES DEPARTMENT OF AGRICULTURE

May 14, 1925

SECTELGTY Of AOTC UtUre = =. ee ee W. M. JARDINE.
Aas siant DS CCLClany= =) 2s eS 2 ee oie R. W. Dunuap.
Director of Scventific Works. 22. 2 ter E. D. Bau.
Director of Regulatory, Work 2. 222. WALTER G. CAMPBELL.
Director of Extension Work: . +222 9i2) se C. W. WARBURTON.
Director of -lijermations2 2216 o2> Stee Netson A. CRAWFORD.
Director of Personnel and Business Adminis-

ARE 1) (Sea a os eR pe peet ne Ph DPMS Tepes vn ee Ke W. W. StockBERGER.
OROUOT 2s ee epee eee ee eo ee R. W. WILLIAMS.
Wicai ler Bureau. 2 fea: Oo, A ess Ae, ph CuHarR Les F, Marvin, Chief.
Bureau of Agricultural Economics___------- Henry C. Tayuor, Chief.
Bureau.of Animal IndusingAs = 4 eek Joun R. Mouter, Chief.
Burcai of lant Industra ss se o£ = Sapa ae Wiuuram A. Taytor, Chief.
MOT est SSCrUlce= a5 a Sau 2 Ree eee W. B. GREELEY, Chief.
BUG Of CREMISYS <i ae a Seen C. A. Browns, Chief.
Buredat of Soilgso ns AVN Bie Ges DBS Minton Wuitney, Chief.
Bureau of Entomology: = 2 eRe na L. O. Howarp, Chief.
Bureau of Biological Survey__.___________- E. W. Neuson, Chief.
Bureau of Public Roads_-__-____- ey eis Br Tuomas H. MacDona tp, Chief.
Bureau of Home Economics____________--- Louise STANLEY, Chief.
PUTCO OF IRIE YONG an on ee ee C. W. Larson, Chief.
Fixed Nitrogen Research Laboratory_______._ F. G. Corrre tu, Director.
Office of Experiment Stations_____________- HK. W. ALLEN, Chief.
Office of Cooperative Work. 222 2 222 ee C. B. Smrru, Chief.
PAIL), «tire. pry te OS ar yt eR NL CLARIBEL R. BARNETT, Librarian.
federal Horkicultural: Boards 4 ose... 28 ne C. L. Maruattr, Chairman.
Insecticide and Fungicide Board _________- J. K. Haywoop, Chairman.
Packers and Stockyards Administration _ ___- Joun T. Caine, in Charge.
Grain Futures Administration____._________ J. W. T. Duve., Acting in Charge.

This bulletin is a contribution from

muneauis, Entomology. oe ee ee L. O. Howarp, Chief.
Fruit Insect Investigations____________ A. L. QUAINTANCE, in Charge.
18

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