Insects in relation to national defense


Material Information

Insects in relation to national defense
Series Title:
Its Circular no. 1-23. Feb. 1941-Jan. 1944
Added title page title:
Insects in relation to national defense, circular
Physical Description:
24 nos. in 1 v. : ill., photos., map, plans, diagrs. ; 23 cm.
United States -- Bureau of Entomology and Plant Quarantine
U.S. Govt. Print. Off.
Place of Publication:
Publication Date:


Subjects / Keywords:
Beneficial insects   ( lcsh )
Insect pests   ( lcsh )
Insecticides   ( lcsh )
Fumigation   ( lcsh )
World War, 1939-1945 -- Health aspects   ( lcsh )
serial   ( sobekcm )
non-fiction   ( marcgt )


General Note:
Reproduced from type-written copy.
General Note:
Includes bibliographical references.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029081698
oclc - 09471812
lcc - SB931 .U44
System ID:

Full Text


Circular 22


i tiU. 4.


June 19/41

'* I, -




Circular 22 Fumigation

Table of Contents

Introduction ................................ 3
Fumigation A Specialized Art .............. 3
All Fumigants Dangerous ..................... 3
Gas Masks .................................. 4
First Aid ................................... 8
Characteristics of the Common Fumigants ..... 9
Carbon Disulphide ..**..................... 9
Carbon Tetrachloride ...................... 12
Chloropicrin ............................. 12
Ethylene Dichloride ....................... 13
Ethylene Oxide *..............*............ 14
Hydrocyanic Acid ............**............ 15
Methyl Bromide ...**...................*... 17
Naphthalene ..**....*..****................ 18
Paradichlorobenzene ....................... 19
Sulphur Dioxide .......................... 19
Fumigation of Warehouses, Barracks, Houses,
etc. ................................... 20
Preparation of the Building ............... 20
Temperature ............................... 21
Time of Application *....... *............ 21
Method of Application ..................... 21
Proper Dosage ............................. 21
Choice of Fumigant .....................*.. 22
Precautions to Take in All Fumigants ........ 22
Danger from Absorbed Fumigants .............. 23

Circular 22 Fumigation 2

Table of Contents (continued)
Warehouse Fumigation with Hydrocyanic Acid ..... 23
Liquid Hydrocyanic Acid ..................... 23
Generating Hydrocyanic Acid Gas from Sodium
Cyanide and Dilute Sulphuric Acid ......... 26
Chemicals Required ......................... 26
Proper Order in Placing Chemicals in
Generator .............. .... .......... 28
The Dosage ................. ......... .... 28
The Generator ................ .............. 28
Placing the Generator ....................... 29
Generating the Gas ......... ................. 29
Emptying the Generators...................... 30
Length of Exposure ......................... 31
Use of Hydrocyanic Acid Discoids .............. 31
Use of Calcium Cyanide ...................... 34
Ventilating the Warehouse after Fumigation .... 36
Warehouse Fumigation with Methyl Bromide ........ 37
Chloropicrin as a Warehouse Fumigant ............ 37
Fumigation of Barracks and Houses with Hydro-
cyanic Acid ............... ..... *.......... .. 38
Fumigation of Barracks and Houses with Chloro-
picrin or Methyl Bromide ..................... 39
Fumigation of Rooms with Sulphur Dioxide ........ 39
Fumigation of Woolens and Furs .................. 40
Naphthalene and Paradichlorobenzene ........... 40
Ethylene Dichloride--Carbon Tetrachloride
Mixture ..................................... 42
Ethylene Oxide--Carbon Dioxide Mixture ........ 42
Fumigation in Tight Chambers or Vaults .......... 43
Vault Fumigation Methods ...................... 41
Fumigation of Dry Staple Foods ................ 46
Fumigation of Cured Meats and Cheeses ......... 47
Fumigation under Tarpaulins ..................... 48
Bin Fumigation .................................. 50
Where Fumigation Chemicals and Equipment can
be Obtained .......................... .. ..... 50
References ........ ..... .................... 54

Circular 22 Fumigation 3


For the control of* insect pests that are
troublesome in barracks, houses, warehouses, store-
rooms, or in foods and fabrics of all kinds that are
stored therein or in other types of enclosures or
storage places, there is no method more quickly ef-
fective than fumigation. By fumigation is meant the
releasing of a poisonous gas or vapor within an en-
closure and maintaining a poisonous atmosphere long
enough to kill any insects present. There are several
fumigants from which to choose, and many factors
governing their successful use. A discussion of the
commonly used fumigants, the uses for which each one
is best adapted, and the various factors affecting
its efficiency and safe use follows:


Fumigation is a specialized operation. Its ef-
fectiveness in insect control depends upon the exact-
ness and skill used in its application. m;ost fumi-
gants are highly toxic and dangerous to handle. Ex-
perience and close attention to details is essential.
It therefore usually is best to have general fumigation
work done by professional fumigators who make a prac-
tice of the art and guarantee their work. All parts of
the country are serviced by reliable fumigation con-
cerns that are available on short notice and have the
proper equipment for doing the work. In some cases and
for certain types of work, defense agencies and other
large organizations may wish to keep a special corps
of workers especially trained to carry on fumigation


Any fumigants that are toxic to insects are also
toxic to human beings. It therefore is necessary to
take every precaution to avoid exposure to heavy con-
centrations of them. If in the application of fumi-
gants it becomes necessary to expose oneself to the
vapors, or if it is necessary to enter a building under

Circular 22 Fumigation 4

fumigation in order to open it for ventilation or
any other purpose, an effective gas mask of the
proper type should be worn.

Gas masks are available, equipped with es-
pecially designed canisters for removing dangerous
vapors from the air breathed through them. A special
canister is required for use with each different
type of fumigant, and it should not be taken for
granted that any canister that happens to be attached
to the mask will afford protection against all gases.
Since the life of a canister is limited, care must be
exercised to see that new ones are supplied whenever
those in use show signs of weakness. Operators
should familiarize themselves with the construction
and use of a gas mask, and should test the mask for
possible leaks before entering concentrations of fumi-
gant s.

It must also be realized that fumigants can be
absorbed directly through the skin so that it should
not be taken for granted that by merely wearing a gas
mask full protection will be obtained. Heavy concen-
trations are particularly dangerous and exposure to
them for more than a few minutes should be avoided
even though a mask be worn.


Gas masks consist essentially of a face piece
and a canister. The most popular and commonly used
type in this country has a breathing tube connecting
the face piece with the canister. In some cases a
skeleton type mask is used, the face piece being elim-
inated. The nostrils are closed by clamps and the
wearer breathes through a rubber device that is in-
serted and held in the mouth.


Circular 22 Fumigation 5

The type popular in this country consists of
a face piece of rubber or rubberized fabric which
can be adjusted to fit tightly across the forehera,
along the cheeks and under the chin, and is con-
nected by a short flexible and non-collapsible tube
to a sheet metal canister containing absorbent ma-
terials. A light harness or knapsack is provided to
suspend the canister from theshoulders or to strap
it to the chest. The face piece is provided with
shatter proof glass eye pieces and with a check valve
through which exhaled air escapes. At the bottom of
the canister is a check valve which opens only to ad-
mit air

For each of the gases likely to be encountered
in fumigation work, an especial canister is available.
Most canisters are charged with materials intended to
absorb only a limited number of closely related gases,
although the all-service canister is designed to af-
ford protection from a combination of gases. A color
code has been adopted by the Bureau of Mines whereby
canisters designed for different gases are assigned
specific colors. A list of gas masks of different
makes that have been tested and approved by the Bureau
of Mines is given in Bureau of Liines Information Cir-
cular 7030.

Information regarding the type and make-up of
canisters used for protection against the fumigants
referred to in this bulletin is given in table 1.

Circular 22 Fumigation 6

Table 1.- Types of canisters used with gas masks for
protection against the common fumigants.

Color of Contents of
canister Protection afforded canister
White Against low concentrations Soda lime, caustic
(less than 2% in air) of pumice, or caus-
acid gases such as Hydro- tite, which is a
cyanic acid*, and sulphur sodium hydroxide
dioxide, preparation, acti-
vated charcoal.

Black Against low concentrations Activated charcoal.
(less than about 2% in air)
of organic vapors such as
carbon disulphide, methyl
bromide, carbon tetrachlo-
ride, ethylene dichloride,
chloropicrin, ethylene oxide.

Yellow Against low concentrations Activated charcoal
(less than 2% in air) of a and soda lime or
combination of organic other alkaline
vapors and acid gases, such granule,
as a combination of hydro-
cyanic acid and cdloro-

Red Against low concentrations Contains a suitable
of combinations of pre- combination of the
ceding gases the all- absorbents men-
service canister, tioned above.

V Vith 2% hydrocyanic acid gas in the air, absorption of the gas
through the skin is rapid enough to cause poisoning after 3
minutes' exposure; 1 percent is dangerous after 10 minutes and
0.5 percent may produce symptoms after 30 minutes.

Circular 22 Fumigation 7

The life of a canister is limited. As sup-
plied by the manufacturer it is sealed by a cap over
the inlet valve at the bottom and by a cork in the
hose nipple. The contents may deteriorate under
some circumstances even without use. If in testing
a gas mask too much resistance to breathing is en-
countered, the canister should be replaced. iith
regard to the life of the all-service canister Forbes
and Grove (1937) make the following statement:

"When poisonous gases, except carbon monoxide,
pass successively into the canister, the canister
expends a portion of its life or capacity in ab-
sorbing each gas. The break or approach to the end
of canister life permits a very small quantity of
poisonous gas to pass, and gradually more and more
passes. The life of the canister when subjected
successively to different gases usually equals the
sum of the part or fractional lives based on the
life for each gas alone but may be longer if the
successive gases are of a different class.

"For example, if the canister were -.sed to one-
half its life or capacity against sulphur dioxide,
it would retain one-half of its original life against
hydrocyanic or other acid gas and more than one-half
its life against organic vapors and anmonia. The
passage of pure dry air does no harm to the life of
the canister against any gas except carbon monoxide.
The respective absorbents fail only when saturated
with absorbed gas or vapors to the point where they
can no longer restrain all the gas that enters.
Poisonous gases can be noticed by odor, taste or
eye irritation. When penetration of a gas is
sensed, the wearer must go to fresh air immediately,
and the canister must be discarded for a new one."

Circular 22 Fumigation 8


In case of poisoning by toxic gases or asphyx-
iation due to lack of oxygen, a doctor should be sum-
moned as quickly as possible. Forbes and Grove (1937)
suggest the following treatment:

1. Remove the victin to fresh air as soon as possible.

2. If breathing has stopped, is weak and intermit-
tent, or is present in only occasional gasps,
artificial respiration, preferably by the prone-
pressure method, should be given persistently
until normal breathing is restored or until it
is definitely believed that the heart action has

3. Circulation should be aided by rubbing the limbs
of the victim and keeping the body warm with
blankets, hot-water bottles, hot bricks, etc.

4. It cannot be emphasized too strongly that inha-
lation of pure oxygen or 5 to 7 percent carbon
dioxide and 95 to 93 percent oxygen, beginning
as soon as possible and continuing for 20 to 30
minutes in mild cases and as long as 1 or 2
hours, if necessary, in severe cases, will
greatly reduce the severity of carbon-monoxide
poisoning and decrease the possibility of serious
after-effects. This treatment will also be help-
ful in gas poisoning or asphyxiation.

5. The victim should be kept at rest, lying down to
avoid strain on the heart;later he should be
given plenty of time to rest and recuperate.

Circular 22 Fumigation 9


Of the many poisonous gases that are toxic to
insects there are a limited number that are particu-
larly well adapted to the needs of the fumigator.
However, not all of these are equally satisfactory
for all types of fumigation work. Some are well
adapted for the treatment of large enclosures, such
as houses, barracks, or warehouses, while others are
suitable only for use in tight vaults or bins. Each
fumigant has different characteristics, a knowledge
of which is essential for their intelligent use. The
physical properties of the common fumigants are given
in table 2 and further discussion of them in alpha-
betical order follows.

Carbon Di sulphide

Carbon disulphide is one of the heavier-than-
air fumigants that is well adapted'for the treatment
of commodities stored in bins or tight containers.
Unfortunately, its value for this purpose is greatly
limited owing to the highly inflammable nature of its
vapors which restricts its use to situations where
the fire hazard can be effectively controlled. The
pure liquid chemical which is about one-fourth heavier
Sthan water, has a sweetish, not unpleasant odor, but
the commercial chemical is often decidedly yellowish
in color, due to the excess of sulphur and has a dis-
agreeable odor due to the hydrogen sulphide contained
in it. On exposure to air it evaporates slowly, form-
ing a heavy vapor that diffuses rapidly downward
rather than upward. Its power of penetrating bulk
commodities is remarkable, a feature which combined
with its high toxicity to insects makes it the most
effective known fumigant for treating bulk grain in

Table 2.- Physical Properties of Common Fumigants

Limit of Lbs. re-
Boiling inflammability quired to
point Liquid in air, Weight saturate
Molec- at density percent per 1,00 cu. ft.
ular 768 mm. (water-l) by volume gallon of space at
Fumigant Formula weight C. at 2000. Lower Upper pounds 77u F.
Carbon di- c
sulphide CS2 76.13 46.3 1.261 1.06 50. 4 10.5 91.2
Carbon tetra-
chloride CC14 153.84 76.8 1.595 13.3 59.1
picrin CCl3NO2 164.39 112.4 1.692 13.8 13.1
Ethylene di-
chloride c2i4cl2 98.947 83.7 1.257 6.2 15.9 10.5 26.4
oxide c0240 44.05 10.7 0.887 3. 80. 7.3 112.5
Hydrocyanic 2
acid HCN 27.03 26.0 0.699 5.6 40. 5.7 66.9 0
bromide CH3Br 94.95 4.6 1.732* 13.5 14.5 14.4 242.4
lene 01018 128.16 217.9 1.145 solid 0.04
benzene C6H 12347.01 173. 1.458 do. 0.5
Sulphur di-
oxide S02 64.06 -10. 1.434* solid 163.7
(sulphur) 0
at 0 degrees 0.

Circular 22 Fumigation 11

Carbon disulphide vapor is highly poisonous
to human beings, producing giddiness, vomiting, con-
gestion, coma and finally death if breathed in con-
centrated form for a protracted period. In its or-
dinary use for treating small quantities of grain
or other ccmmodities in bins or tight boxes the
worker is not likely to experience more than a slight
giddiness. The first symptoms of carbon disulphide
poisoning are a numbing of the senses, the power of
thought is weakened as well as hearing and sight.
More or less dizziness occurs and the fumigator works
in a mechanical sort of way. Men working where the
gas is present should get out into the fresh air at
the first signs of dizziness.

As previously stated, the vapors of carbon di-
sulphide in admixture with air are highly inflammable
and explosive and may ignite from any form of fire or
even without the presence of flame at temperatures of
2120 F. or above. Fire insurance is void while carbon
disulphide is being used. It should be remembered
that lighted lanterns, igars, pipes, cigarettes, pilot
lights in gas stoves and heaters, sparks from electric
switches, static or frictional electricity, sparks
caused by hammering upon metal, or even hot steam
pipes may cause an explosion of the vapor. For this
reason it should be used only for the treatment of
bins, boxes and small enclosures segregated from build-
ings and where danger from fire can be avoided.
Carbon disulphide ranges in cost from about
6 cents a pound in 500-pound lots to 30 cents a pound
or more in 1-pound lots. Firms dealing in chemicals
and insecticides usually sell it in 5-gallon cans for
about 95 cents a gallon.

Circular 22 Fumigation 12

Carbon Tetrachloride

Carbon tetrachloride is a colorless, ncL
inflammable liquid, with a pungent, aromatic ocor.
It evaporates, but slowly, when exposed to air,
forming a vapor that is not highly effective against
insects when used alone. Its chief value is for mix-
ing with more toxic fumigants, such as ethylene di-
chloride, to reduce the fire hazard, and with less
volatile fumigants, such as chloropicrin, to hasten
vaporization and aid distribution by increasing the
volume of the fumigant. It has an anaesthetic effect
upon man, similar to chloroform, and while not highly
toxic in weak concentrations, care should be taken
not to expose oneself to the fumes of this fumigant
or any mixture containing it for any extended period
without wearing a gas mask.


Chloropicrin may be used as a general fumigant
for large enclosures, such as houses, or warehouses,
for the treatment of grain in bins and for other bulk
commodities in vaults. It is a colorless or slightly
yellowish liquid, a little more than one and one-half
times as heavy as water, that volatilizes slowly on
exposure to air.

Chloropicrin is non-explosive and non-inflammable
as ordinarily used for fumigating purposes, and is ex-
tremely toxic to insects. It has the disadvantage of
being slow in action, difficult to vaporize and dis-
agreeable to handle because its vapor is a very
irritating tear-gas and has a nauseating effect. Its
vapor clings tenaciously to fumigated commodities and
seriously affects the germination of grain and seed if
the moisture content is high. When present in flour,
chloropicrin has a deleterious effect on its baking
qualities. This effect disappears when the flour is

Circular 22 Fumigation 13

The eye-irritating property of chloropicrin
vapor is such that it is improbable that anyone
wuld willingly enter an atmosphere containing an
appreciable quantity of it. A gas mask with properly
designed canister should always be worn while apply-
ing this material and care should be taken not to
spatter the liquid on the hands or feet, since
blistering of the skin may result.

According to Underhill (1919), the toxic ac-
tion of chloropicrin to man is somewhere between that
of chlorine and phosgene. Exposure to the gas causes
coughing, nausea and vomiting and in large quantity,
it may cause unconsciousness. Secondary effects are
bronchitis, shortness of breath, a weak, irregular
heart beat, and gastritis. It may also cause acute
nephritis. Chloropicrin injures the lining of the
respiratory tract, especially the medium and small
bronchi. An overwhelming edema of the lungs rapidly
follows exposure to a lethal concentration of the gas.
Splashes of chloropicrin on the skin may be washed off
with alcoholic di-sodium sulphite to prevent ulcera-
tions. Affected eyes may be bathed with boric acid
or a 2 percent solution of sodium bicarbonate.

Chloropicrin can be purchased in one-pound glass
bottles or in cylinders of from 1 to 100 pounds ca-
pacity at a cost of $1.20 per pound for 1-pound cyl-
inders down to 85 cents per pound in 100-pound lots.

Ethylene Dichloride

Ethylene dichloride is particularly useful as
a fumigant for stored grain and seed in bins, and for
the treatment of fabrics, garments, and furs in vaults
or other tight containers. Although its vapors are
inflammable it has been found that by mixing it with
carbon tetrachloride in the proportion of 3 parts by
volume of the ethylene dichloride to 1 part by volume

Circular 22 Fumigation 14

of carbon tetrachloride a non-inflammable mixture
is obtained. This, from the standpoint of fire
hazard, is safe to use under all ordinary condi-

Ethylene dichloride is a colorless liquid
with an odor somewhat resembling chloroform. On
exposure to air it vaporizes rather slowly and if
applied to the surface of a bin of grain the vapors
will penetrate to all parts of the bin in a satis-
factory manner. It can be used to treat seeds of
all kinds without fear of injury to the germination
regardless of the dosage and exposure, and is harm-
less to fabrics. The vapors are not quickly toxic
to man in concentrations ordinarily used, but they
have an anaesthetic action and care must be taken
to avoid exposure to them for an appreciable period
without using a gas mask.

Ethylene dichloride in admixture with carbon
tetrachloride can be purchased in 55-gallon drums
for about 6 1/2 to 7 cents per pound. In smaller
quantities it can be purchased for about 75 cents
per gallon.

Ethylene Oxide

Ethylene oxide is suitable for the treatment
of many commodities in atmospheric vaults. It does
not injure fabrics or furs or leave any obnoxious
odor or poisonous residue on food stuffs. The con-
centrated vapcr of ethylene oxide is inflammable
but concentrations up to 3 1/2 pounds per 1,000
cubic feet of space are non-explosive and non-
inflammable. Although it is used alone for some
purposes it is better to use it in admixture with
carbon dioxide. A non-inflamiable mixture consist-
ing of 1 part by weight of ethylene oxide to 9 parts
of carbon dioxide is available commercially and is
excellent for use in atmospheric vaults.


Circular 22 Fumigation 15

Ethylene oxide is a colorless liquid- at low
temperatures but on exposure to air it evaporates
with great rapidity. It is supplied in cylinders
under light pressure. As ordinarily used the dangers
from breathing the vapors of ethylene oxide are not
considered to be great. However, precautions taken
against breathing tue vapors should be the same as
with any dangerous gas.

The liquid ethylene oxide is marketed in
cylinders containing 75 or 195 pounds at a cost of
about 26 cents per pound f.o.b. the factory. In
smaller quantities the cost is higher. The mixture
of ethylene oxide and carbon dioxide is sold in 30-
and 60-pound cylinders under high pressure at prices
ranging from 14.5 to 16 cents per pound, f.o.b. the

Hydrocyanic Acid

For the fumigation of all types of buildings,
such as houses, barracks, or warehouses, there is no
more efficient gas than hydrocyanic acid. Since it
kills with great rapidity it can be successfully used
in enclosures that are incapable of holding fumigants
for long periods and in which other less toxic gases
are useless. It is also excellent for use in atmos-
pheric vaults and will not injure most articles of
conraerce. It is a deadly poison but can be handled
with reasonable safety by experienced fumigators.
Hydrocyanic acid is a colorless, volatile liquid that
is inflammable and that burns like alcohol when ig-
nited. In the vapor stage, when mixed with air at
concentrations used in ordinary fumigation it is non-
inflammable and non-explosive.

In fumigation work hydrocyanic acid gas is
commonly produced in four ways: (1) by the evapora-
tion of the liquid acid pumped into the enclosure

Circular 22 Fumigation 16

from cylinders; (2) by generating it in a barrel or
other container from a mixture of sodium cyanide and
dilute sulphuric acid; (3) by evaporating it from
discoids of an absorbent material impregnated with
the liquid; (4) by exposing to the air, in thin
layers, a powder consisting of calcium cyanide, which
combines with the atmospheric moisture to produce
hydrocyanic acid gas.

Owing to the high toxicity of hydrocyanic acid
the cost of fumigating with it is not high. The cost
will vary, however, with the method by which the gas
is produced. It is cheapest when generated by the
barrel method. Liquid hydrocyanic acid is sold for
$1 per pound. Sodium cyanide can be purchased in
100-pound lots for about 16 cents per pound and sul-
phuric acid for approximately 4 cents per pound in
11-gallon carboys. Discoids sell for 1.20 per pound
in one-pound cans. Calcium cyanide dust containing
50 percent available hydrocyanic acid ranges in price
from 81.60 per one-pound cans to $1.20 per pound
in 25-pound cans.

*With regard to the effect of hydrocyanic acid
on man, Flury and Heubner state that from 40 to 50
milligrams of hydrocyanic acid per cubic meter are
tolerated without serious injurious after effects.
The latter concentration may produce headache, nausea,
and vomiting. Sixty to 70 milligrams of HCN per cubic
meter constitute the danger limit and 100 milligrams
per cubic meter (about 1/10 oz. per 1,000 cubic feet)
and over may cause death. According to the U. S.
Public Health Service (1929), concentrations of from
140 to 180 milligrams per cubic meter are dangerous
on exposure from 30 minutes to one hour, and exposure
to concentrations greater than this kills in a short

Circular 22 Fumigation 17

Methyl Bromide

Mlethyl bromide is useful as a general fumigant
for buildings of modern, tight construction and for
the treatment of certain bulk commodities in atmos-
pheric vaults. It does not kill insects so rapidly
as hydrocyanic acid, hence is not effective in loosely
constructed buildings that are incapable of holding
the gas for any appreciable length of time. It is
not recommended for the fumigation of foodstuffs that
have a high fat "ontent or for milled cereal products
intended for human consumption since these products
retain quantities of residual bromides that may be

iethyl bromide is a colorless gas that is sold
commercially in liquid form in cylinders. It is under
sufficient pressure so that a cylinder will empty it-
self if the valve is opened. It is non-inflammable
at concentrations used in commercial practice, pene-
trates bulk commodities with remarkable facility and
can be used successfully at comparatively low tempera-
tures. It lacks a distinctive odor and is but faintly
noticeable in small amounts, a feature that creates a
hazard not present with some of the rapidly toxic
gases that possess distinctive warning properties.

According to the United States Public Health
Service (1929), "It is a little more toxic than gaso-
line, chloroform, and carbon tetrachloride for very
short exposures and is markedly more toxic than these
compounds in exposures of 30 minutes or more." Expo-
sure to the gas may result in nausea, vertigo, visual
disturbances, headache, loss of appetite and, in se-
vere cases, to paralysis of the extremities, delirium,
convulsions, epileptiform attacks or even death.

Referring to the human hazard connected with
the use of methyl bromide for fumigation, the United
States Public Health Service (1938) states that

Circular 22 Fumigation 18

"while methyl bromide is less toxic to man than cer-
tain fumigants, all persons fumigating with methyl
bromide or mixtures containing methyl bromide; or
persons entering fumigated rooms, cars, or sheds to
open ventilators or to unload fumigated materials,
should observe precautions used with other toxic
fumigating gas. Experience indicates that adequate
precautions will obviate danger of injury by this

Methyl bromice is obtainable in one-pound
cans or in cylinders containing 10, 50, or 150 pounds
net. In 50-pound cylinders it sells for 70 cents per


Naphthalene is useful chiefly in tightly clo-^C
containers or small rooms for the long time protection
of clothing, furs, and woolen fabrics. It is a white,.
crystalline substance that on exposure to air sublimes
slowly forming a vapor that is toxic to insects con-
fined in it. It is not a quick acting fumigant, but
will afford long time protection to clothing stored in
tight containers if a sufficient quantity is used to
compensate for any loss from leakage. It is more eco-
nomical for this purpose than paradichlorobenzene since
only .04 pound of the material is required to saturate
the atmosphere in 1,000 cubic feet of space at a tempe-
rature of 770 F. It should not be used to fumigate
grains or other food products since the vapors impart
an odor and taste that is retained. The flesh of
animals and poultry fed on materials fumigated with
naphthalene becomes tainted with a characteristic,
disagreeable flavor. The vapors of naphthalene are
non-inflammable and-are not considered to be dangerous
to human beings, at least for short exposures.

|l-s,~,i ,I ,,,,,,;

............ .. .-! .. .. ... ........ .... .

CirQular 22 Fumigation 19

Paradi oh lorobenzene
Paradiohlorobenzene is employed in the same
manner and for the same purposes as naphthalene.
It is not quite so economioal as the latter material
since it requires .5 pound to saturate the atmosphere
in 1,000 oubic feet of space. It is a white crystal-
line material that, on exposure to air, sublimes
slowly forming a heavy vapor that has an odor more
pleasing to some people than that of naphthalene.
The vapor is non-inflamable as ordinarly used* How-
ever, it will flash at about 1580 F. With respect to
food products it has the same unfortunate character-
istics as naphthalene in that it imparts an obnoxious
odor and taste that with animals and poultry is
carried through to the flesh.

Sulphur Dioxide
Sulphur dioxide has a limited use for the treat-
ment of empty buildings or rooms in barracks and houses
that do not contain materials likely to be injured by
the bleaching or corrosive effeots of the fumes. It
is usually produced in fumigation work by the burning
of sulphur, although it can be obtained in liquid form
in oylinders. It is non-inflammable, highly toxio to
insects, and, like hydrooyanio acid, is rapid in action.
The irritating effects of even low concentrations makes
it unlikely that human beings will willingly enter a
dangerous concentration. When breathed it is quickly
absorbed by the moist surfaces of the respiratory tract
resulting in severe inflammation and edema.

Circular 22 Fumigation 20


In the fumigation of large enclosures, such
as warehouses, barracks, houses, and similar build-
ings, success will depend largely on the proper prep-
aration of the building, the coi-ecL choice of a fu-
migant, the use of an adequate supply of the fumigant,
its proper application and the circumstanceu ,.r
which it is used. The various factors involved will
be discussed in order.

Preparation of the Building

It is essential that the building or room be
as nearly air-tight as it can be made. All windows
should be tightly wedged or sealed, and any broken
panes replaced. Loosely fitting window sashes should
be sealed with paste and paper or "puttied up" with
flour and oil mixed to the consistency of putty. For
stripping window frames several types of material can
be used: rolls of gunmmed paper, strips of newspaper
smeared with grease or pasted with flour paste, or
rolls of fumigators' tape are suitable. Sometimes i
is impossible to tighten a window by the ordinary
method of sealing or stripping and it is necessary to
seal the entire aperture. For this purpose, car-lining
paper can be used or, better still, fibre-reinforced,
tar impregnated paper.

Small doors leading to the exterior of the
building can be tightened with any of the materials
used for the windows. Large slicing metal or wooden
doors that fit itrfectly can be caulked with the flour-
and-oil mixture or with a paste composed of 4 parts of
asbestos to 1 part of calcium chloride mixed with a
little water. Both these mixtures form an effective
seal, yet can be easily removed after fumigationo

Roof ventilators should be thoroughly sealed,
also chimneys and other flues.

Circular 22 Fumigation .21


At high temperatures all gases are more active
and efficient, and insects are likewise more active
and susceptible, hence it is desirable to mainAain a
high temperature in the building during the fumiga-
tion. For best results a temperature of at least 750 F.
is desirable, although with hydrocyanic acid or methyl
bromide it is possible to obtain good results at tempe-
ratures as low as 550 F., if it becomes necessary to
fumigate under such conditions.

Time of Application

High winds cause the fumigant to drift to one
side of a building and to increase the rate of leakag .
Fumigation during periods of little or no air movement
is desirable.

Method of Application

For best results the fumigant should be applied
so that a maximum concentration will be obtained as
quickly as possible. This is particularly important
in buildings in which the leakage factor is high.

Proper Dosage

In the case of warehouses or store rooms that
are filled with highly absorptive commodities, such as
feed, it is necessary to use a larger dosage than if
it were empty. Similarly a poorly constructed building
will require a larger dosage to offset leakage. The
experience of the fumigator plays an important part in
deciding the dosage.

Circular 22 Fumigation 22

Choice of Fumigant

From the standpoint of availability, cost,
efficiency, and simplicity of application, hydro-
cyanic acid is the most practicai gas for the general
fumigation of houses, barracks, warehouses, And 1hiild-
ings of all kinds. Methyl bromide can be used f the
building or enclosure is of modern, concrete or brick
construction, and in certain cases sulphur dioxide is
useful for the treatment of rooms in barracks or
houses. Chloropicrin, although less popular than hy-
drocyanic acid and methyl bromide, owing to the lachry-
matory nature of the fumes and the tenacity with which
they cling to fumigated commodities, can also be em-


In the fumigation of warehouses, barracks,
houses, or any structure, it is necessary to take cr -
tain precautions to safeguard persons that are likely
to be in the vicinity of the building on business or
otherwise. Before the fumigant is introduced the build-
ing must be searched to determine that no persons are
left inside. Adequate warning signs should be posted,
the building locked up and guards posted to prevent
the entry of anyone after the gas is introduced and for
the entire period that the building is under fumigation.
During ventilation the guards should be instructed to
prevent anyone besides the fumigators from entering
the building until it has been declared free from gas.

If the building to be fumigated adjoins other
buildings, these should be vacated during the fumiga-

Circular 22 Fumigation 23


Many commodities stored in warehouses that
are fumigated absorb large quantities of the fumi-
gant which are slowly given off after the fumigation
is over. If warehouses or rooms that have been fii-
migated and ventilated are closed up tightly, it is
quite possible that fumigated commodities stored
therein may give off a sufficient amount of gas to
be dangerous to anyone entering the building at a
later date. If possible warehouses or rooms that
contain large quantities of fumigated commodities
should be kept open for several days to allow the
dangerous vapors to escape.


Hydrocyanic acid gas is the most efficient
fumigant known for the treatment of structures that
are not completely air-tight, since it kills with
great speed. It is relatively inexpensive, will not
injure the dry staple foodstuffs, and is non-
inflammable at concentrations used in warehouse fu-
migation. Although it is one of the most deadly gases
used in fumigation work it can be handled with rela-
tive safety by experienced workers. It is commonly
produced in several different ways, but for use in
warehouse fumigation it is best produced by pumping
it into the building in liquid form from cylinders
or by generating it from a mixture of sodium cyanide
and dilute sulphuric acid.

Liquid Hydrocyanic Acid

Liquid hydrocyanic acid is more convenient to
use for warehouse fumigation than the barrel or pot
method by which the gas is generated from sodium cya-
nide and dilute sulphuric acid. Liquid hydrocyanic

Circular 22 Fumigation 24

acid can be used wherever a supply of it can be ob-
tained. In outlying posts it is not always practi-
cal to use it since the liquid has a tendency to
decompose with time and it is not considered safe
to store the cylinders for more than 5 months.

After a building has been prepared for fumi-
gation, the liquid hydrocyanic acid is applied en-
tirely from the outside, figure 1. A portable com-
pressor attached to the cylinder forces the gas into
the building by means of lines of pressure rubber
tubing, or metal piping equipped with spray nozzles.
For permanent installations in warehouses, copper
tubing is used to pipe the building, a spray nozzle
being provided for every 15,000 cubic feet. For
temporary work the easily transported rubber tubing
is adequate.

Each cylinder of liquid hydrocyanic acid is
supplied with an inlet and an outlet valve. The out-
let valve is attached to a steel tube connected with
the bottom of the cylinder. The inlet valve leads
directly into the top of the cylinder, and when the
fumigation is about to begin, air is pumped through
it into the cylinder by means of a compressor until a
pressure of about 100 pounds is obtained. The outlet
valve, which in the meantime has been connected with
the inlet pipe to the building, is then opened and
the liquid is forced into the building. The pressure
must be maintained until all the liquid has been
blown through the pipes into the building. The pipe
lines are then blown clear and the inlet tubes capped.

While applying the gas the fumigator should
wear a gas mask or have one handy to put on in case
of leaks or breaks in the pipes, and should wear pro-
tective outer clothing that can be slipped off easily
in case it accidently becomes soaked with the liquid.

Circular 22 Fuwmgation 25

the liquid method. The liquid hydrocyanic acid in the cylindero
the scales is being forced by air pressure generated by a small
electrically driven compressor, through the rnbber tubing from t
cylinder to the piping system installed. inside but protrudng
through the walls.

~ iIlk

Ij E


Figue l.-Ihmgatig a arehuse ith idr(cyP-i- c .-i
th iqi mtod helqudkyrcyn -aC-4 ''
the cals isbeig focedby ar pess,.,r gere-rf'e

elcrclydie opesr hog
cyinertote ipngsytm nsa-e'
through he walls

Circular 22 Fumigition 26

A dosage of 8 ounces of liquid hydrocyanic
acid for every 1,000 cubic feet of space is adequate
for the treatment of empty warehouse space, or space
filled with clothing and commodities other than
bagged foodstuffs. Warehouses loaded with large
quantities of bagged flour, feed, grain or similar
materials are difficult to fumigate successfully with
even very heavy dosages of hydrocyanic acid.

Generating Hydrocyanic Acid Gas from Sodium Cyanide
and Dilute Sulphuric Acid

This method is cheaper, though more laborious,
than the use of liquid hydrocyanic acid as described
above, but can be used where supplies of liquid hydro-
cyanic acid are not available.. It is known as the
barrel or pot method because the chemicals used in
the process are placed together in a barrel or similar
container, figure 2.

Chemicals required.- Sodium cyanide (96 to 98
percent, containing 54 percent of available HCN), a
commercial grade of sulphuric acid (660 Baume), and
water, are the only materials required. For best re-
sults they should be mixed according to the following

Sodium cyanide . . 1 pound
Sulphuric acid . . . 1 1/2 pints
Water,... 2 pints

Sodium cyanide is a white crystalline substance,
which for fumigation purposes is prepared in egg-shaped
lumps weighing approximately one-half ounce or 1 ounce
each. It is a violent stomach poison, and also can
cause serious poisoning by being absorbed through open
cuts or through the mucous surface of the eyes. For
this reason it is best handled with a scoop or shovel
or with gloved hands.

Circular 22 Fumigation 27


Figure 2.--4an wearing gas mask about to lower a bag of sodium
cyanide into a barrel containing sulphuric acid and water.

Circular 22 Fumigation 28

Sulphuric acid is a heavy, colorless liquid
when pure, but the commercial acid used in large-
scale fumigation work is slightly discolored, or
murky, owing to impurities. It is highly corrosive
and will cause injury if it spatters on the clothing
or body of the operator or upon the floor. It can
be purchased in 11-gallon carboys. When large quan-
titles of acid are required, a tilting frame will be
found convenient in pouring the acid from the carboys,
or an acid pump can be used.

Proper Order in Placing Chemicals in Generator.-
To generate hydrocyanic acid gas by this method, the
operator should first pour the water into the genera-
tor and then add the acid. If the procedure is re-
versed, the reaction is so violent that the operator
may be dangerously burned by the spattering of the
acid-water mixture. As soon as the sodium cyanide
comes in contact with the mixture of water and acid
an immediate chemical reaction takes place during
which hydrocyanic acid gas is given off. The pure gas
is colorless, but when mixed with steam produced by
the chemical reaction it has the appearance of a light
bluish amoke. It has an odor resembling that of peach

The Dosage.- The dosage is computed on the basis
of the quantity of sodium cyanide required. For ware-
house fumigation one pound of sodium cyanide will pro-
duce enough gas to fumigate 1,000 cubic feet of space,
if the building is of reasonably tight constr :-tion.

The Generator.- For large-scale ml1gZEicon a
water-tight 50-gallon heavy wooden barr.-. is the most
suitable generator to use. Metal contaaners must not
be used because of their susceptibility to corroc' n
by the acid. Each barrel will hold a maximum cha. -e
of 30 pounds of sodium cyanide, or enough to fumie 'e
30,000 cubic feet of space. When it is necessary
fumigate small rooms of a few thousand cubic fet

Circular 22 Fumigation 29

separate units, earthenware or stone jars of appro-
priate size can be used, A 4-gallon jar will hold
a charge of 3 pounds of sodium cyanide.

Each generator should be set in a galvanized-
iron washtub in which has previously been placed a
pailful of water containing several handfuls of
washing soda. This precaution provides for catching
and neutralizing snall quantities of the acid-water
mixture that may leak out of the barrel.

If three or four bricks are placed in the
bottom of the washtubs for the barrels to rest on,
they will not become stuck in the tubs.

Placing the Generators.- If possible, the
generators should be spaced evenly over the floors to
obtain an even distribution of the gas. If necessary,
however, the generators for one floor can be grouped
together near the exit. The gas will eventually be
dispersed to all parts of the enclosed space, though
not so rapidly as when the generators are scattered
evenly over the flooro

Generating the Gas.- After the warehouse has
been prepared for the fumigation and all the genera-
tors have been placed in their proper positions, the
water and acid are measured out and distributed. The
acid can be poured from the carboys into heavy galva-
nized-iron buckets, which will resist the action of
the acid long enough for it to be distributed without
accident. If jars are used for generators, the acid
must be poured into the water slowly, lest the heat
developed by the chemical reaction between the water
and acid cause the jars to break.

After it has been determined that none of the
barrels leak, the sodium cyanide, which has been
weighed in the proper quantities and placed in paper
bags, should be placed beside the generators. The

Circxlar 22- Fumigation 30

sodiu cyanide should not be placed in the bags until
the latest possible moment; otherwise, the cyanide
takes up moisture from the atmosphere, thus softening
the paper so that the bags may break when lifted.

When all the precautionary measures have been
taken, and as soon as possible after the water and
acid have be ixed, the fumigating crew, starting
with the generator farthest from the exit and on the
top floor in the case of a building of more than one
story, hould loer the bags gently into the genera-
tors. The man in charge should not take part in the
lowering of the cyanide, but should watch the crew
to see that none of the generators is skipped, and
that none of the men gets into trouble.

Since the gas is generated as soou as the acid-
water mixture coms in contact with the sodium cyanide
the supervisor and operators engaged in droping the
yanide shoud ar gas masks.

mptying the Generators.- When the fumigation
is finished and te building has been thoroughly
ventilated, the residue must be emptied from the gene-
rators. Sotmes the chemical reaction is incomplete,
because some of the sodium cyanide has not come in
iontact with the acid-water Mixture. When the genera-
tor is moved, the contents are shaken up and small
uantities of gas ma be given off. For this reason
the operator should breathe as little as possible while
handling the barrels and should not hold his head over
the barrel.

The residue, which is poisonous, can be dis-
posed of by pouring it into a hole in the ground and
cveri s it with soil. When disposing of the residual
material after fumigation, the operator should never
bend over the hole, but should stand to windward and
lean away from the hole as much as possible.

Circular 22 Fumigation 31

Length of Exposure.- The efficiency of a fumi-
gation is proportional to the length of exposure and
if the fumigant can be held in an enclosure a long
exposure period is desirable. However, few buildings
will hold an appreciable concentration of hydrocyanic
acid for more than 24 hours, hence it is rarely prac-
tical to extend the exposure for a longer period. On
the other hand it is possible to obtain excellent re-
sults in much shorter periods and a 12-hour period
may suffice if time is short,

Use of Hydrocyanic Acid Discoids

For the treatment of small warehouses or stor-
age rooms hydrocyanic acid discoids will be found con-
venient and useful, although their use is not recom-
mended for any but professional fumigators. Wafer-
like discoids of an inert material, each containing
approximately one-half ounce of absorbed liquid hydro-
cyanic acid, are available packed in sealed metal cans
of various sizes, and sold on the basis of the net con-
tent of hydrocyanic acid. When the cans are opened
and the discoids scattered over the floor the liquid
hydrocyanic acid evaporates and diffuses to all parts
of the enclosure.

The proper number of cans of discoids should be
placed in each room or floor of the warehouse if there
are more than one, and fumigation should be started on
the top floor or the room farthest from the exit. One
man should open the cans, using a special can opener
(figure 3) that makes a clean cut close to the rim,
vhile two or more men, if necessary, take the open cans
and scatter the discoids over the floor. (figure 4).

Discoids should not be placed directly on
painted or varnished floors or woodwork, for the liquid
hydrocyanic acid is likely to injure the finish. A
layer of two or three thicknesses of paper provides

Circular 22 Fumigation 32

Figure 3.-- Man protected by gas mask, removing the top from a
tin can containing discoids impregnated with liquid hydrocyanic

Circular 22 Fumigation 33

Figure 4.- Turnished room being fumigated with hydrocyanic
acid gas generated from discoids. The discoids are shown
scattered over a piece of paper to prevent any liquid from
coming in contact with the floor.

adequate protection against any liquid that may ooze
from the discoids. When discoids are used, the fumi-
gators are exposed to a certain concentration of the
gas while they are opening the cans and distributing
the contents. Good gas masks will protect them agains'
poisonous fumes, but there is also some danger frc
the direct absorption of hydrocyanic acid gas throt.
the skin. The fumigating crew zhould be large enough

Circular 22 Fumigation 34

so that the distribution of the fumigant will be
speedy and no one man will be exposed to the gas
for a dangerously long period.

When large numbers of discoids are used, it
is advisable to chill the cans before fumigating.
This retards the evolution of the gas and thus in-
creases the safety of the operation. If solid car-
bon dioxide or "dry ice" is available, a liberal
quantity thrown over the tops of the cans in each
open case a few hours before fumigation will chill
the discoids.

As in the case of liquid hydrocyanic acid, a
dosage of 8 ounces per 1,000 cubic feet of space
should be used for general fumigation purposes.

After the fumigation and ventilation of the
building, the spent discoids and the empty cans can
be gathered and disposed of. At the end of a 24-
hour fumigation the discoids do not retain more than
a trace of hydrocyanic acid.

Use of Calcium Cyanide

Calcium cyanide in dust form is used in much
the same way as the discoids for the treatment of
small warehouses or enclosures. On exposure to air
the powder absorbs moisture and a chemical reaction
takes place by which hydrocyanic acid gas is given

Applying the Powder.- The required number of
cans of calcium cyanide are distributed throughout
the building. They are then opened and their con-
tents scattered over the floor in a layer not more
than half an inch thick. To facilitate removal of
the dust after the fumigation, it may be scattered

Circular 22 Fumigation 36

on strips of paper previously laid on the floor, al-
though it is sometimes placed directly upon the floor
(fig. 5). Each can of fumigant is equipped with a
special perforated top, which the fumigator puts in
place of the friction top when he is ready to use it.

Figure 5.--Warehouse being fumigated with hydrocyanic acid
gas generated from calcium cyanide. The calcium cyanide in
dust form is spread on the floor, usually from cans with
perforated covers.

Inasmuch as the gas is given off very rapidly
after the dust is exposed to the air, the fumigator
should wear a gas mask while distributing it. As in
the case of the discoids, he should begin distributing
the dust at the point farthest from the exit, so that
he will be working away from the gas that is being
given off.

Circular 22 Fumigation 36

After the fumigation, the paper on which the
dust is spread can be rolled up and thrown away, or
the dust can be swept from the floor and placed in
containers, to be disposed of immediately. The res-
idue, which is mostly calcium hydroxide, is likely
to absorb some of the hydrocyanic acid from the air;
hence it is advisable to dispose of it outside the
building, where small quantities of escaping hydro-
cyanic acid gas will harm no one. After the hydro-
cyanic acid has been given off, the residue is non-
poisonous. As the dust may be blown about while the
building is being ventilated, it should be removed
as soon as possible.

To calculate the quantity of calcium cyanide
needed for a fumigation, it is necessary to know the
percentage of available hydrocyanic acid it contains.
This percentage will be found on the label of the can.
If, for example, the dust contains 50 percent of
available hydrocyanic acid, 1 pound will give off as
much gas as 8 ounces of liquid hydrocyanic acid or
1 pound of sodium cyanide. Calcium cyanide ranges
in price from l1.60 per pound in 1-pound cans to Y1.20
per pound in 25-pound cans.

Ventilating the Warehouse after Fumigation

After the fumigation and regardless of the
method used to generate hydrocyanic acid gas the build-
ing should be aired out by opening the doors and
windows. If possible these should be opened from the
outside. If not, windows and doors can be opened from
the inside by workmen wearing gas masks. In this
latter operation two men should work together to guard
against accident.

Circular 22 Fumigation 37


For the fumigation of modern concrete or
brick warehouses of tight construction, there is
no better fumigant than methyl bromide. It is ex-
cellent for the treatment of empty warehouse space
or space filled with bagged, whole grains or feeds.
It should not be used to treat warehouse space
loaded with milled cereals or foods with a high fat
content that are intended for human consumption.

It can be applied in very much the same manner
as liquid hydrocyanic acid by being forced through a
temporary or permanent piping system, or in small
warehouses the cylinders can be placed inside the
warehouse and the gas released by opening the valves.
Sufficient air pressure is added by the manufacturer
to insure the ejection of the fumigant from the cyl-
inders when the valve is opened unless the liquid has
to be forced through a system of pipes and spray
nozzles. In that case the pressure in the cylinders
should be increased to 150 pounds by means of com-
pressed air. A dosage of 1 pound of the liquid per
1,000 cubic feet of space is sufficient for both
empty and filled warehouses.

An overnight fumigation is sufficient, after
which the warehouse can be opened for ventilation.
The same precautions should be taken in opening up
warehouses fumigated with methyl bromide as with
those fumigated with hydrocyanic acid.


For the treatment of empty warehouse space
chloropicrin can be applied at the rate of 1 pound
per 1,000 cubic feet of space. The liquid chloro-
picrin can be drawn off from the 100-pound cylinders
into 6-quart sprinkling cans by workmen wearing gas

Circular 22 Fumigation 38

masks and applied by sprinkling on burlap sacks
spread on the floor. Care should be taken to keep
the liquid from coming into contact with varnished
woodwork. Care must also be taken to avoid spatter-
ing the liquid on the hands or feet, since blistering
may result.

As is the case with other toxic fumigants
that are applied by hand, it is desirable to start
applying the material at the point most distant from
the exit and gradually work toward the door.

The same precautions must be observed in'open-
ing the building for aeration after the fumigation as
employed with any other poisonous gas. Considerable
time, sometimes several days, is usually required to
ventilate a building after fumigating with chloropic-
rin owing to the tenacity with which the vapors cling.


In the fumigation of barracks and houses with
hydrocyanic acid for the control of bedbugs, cock-
roaches, clothes moths, carpet beetles, or other
household pests, the same methods can be employed as
described for the fumigation of warehouses. It is,
of course, unlikely that there would be any occasion
to permanently pipe a house or barracks for the use
of liquid hydrocyanic acid, but temporary lines of
pressure rubber hose can be used to conduct the liquid
fumigant to all parts of a building. Mviany fumigators
prefer to use the "barrel" method of generating the
gas for the treatment of small buildings,although the
use of discoids is also popular. In any case the same
precautions must be taken to safeguard the fumigators,
and to prevent people from entering the building while
it is under fumigation, as described for warehouse

Circular 22 Fumigation 39

In houses or barracks, mattresses, bed cloth-
ing, and other furnishings may retain enough hydro-
cyanic acid after a fumigation to be dangerous to
people using them or confined in rooms with them.
This is particularly true during cold weather. After
a fumigation has been conducted under such conditions,
and the rooms of the building have been ventilated,
the heat should be turned on and the contents allowed
to warm up so that the gas held by the mattresses,
blankets, etc. will be given off. The rooms can then
be aired out again and the windows left open until
there is no more danger. If possible, fumigated
blankets and mattresses should be taken outdoors
where they can be beaten and aired thoroughly before
being used.


In a similar way houses, individual rooms or
barracks can be successfully treated with either
chloropicrin or methyl bromide and at the same dos-
ages and periods of exposure recommended for warehouse
fumigation. Methyl bromide should be used only in
tight buildings of concrete, stone, or brick construc-
tion. Any leather goods should be removed from the
buildings before fumigation, since it has been found
that in some cases leather products retain a peculiar
odor after fumigation with this gas. It will be found
that chloropicrin clings tenaciously to fumigated fur-
nishings so that it may take several days in some cases
to entirely get rid of the eye-irritating vapor in the
air of a fumigated building.


The burning of sulphur in rooms or houses is
one of the oldest known methods of fumigation. It
is rather difficult to confine the heavy vapors unless
the room is exceptionally tight, and the gas


Circular 22 Fumigation 40

itself is not so toxic as hydrocyanic acid. Fumiga-
tion with sulphur dioxide is quite simple, however,
and is considered to be safe owing to the fact that
the fumes are so irritating that nobody will willing-
ly stay in a concentration strong enough to be danger-

Sulphur dioxide is usually generated by burn-
ing sulphur. For the fumigation of houses or rooms,
sulphur candles may be purchased ready for burning.
Since sulphur alone does not burn readily it is often
dampened with alcohol to hasten the process, bulphur
dioxide is non-inflammable, but there may be danger
unless precautions are taken to prevent the burning
sulphur from setting fire to the Surroundings. Two
pounds of sulphur should be burned for every 1,000
cubic feet of space. The room should be kept closed
for 12 to 24 hours before being aired.

Sulphur dioxide fumes corrode metals, bleach
fabrics and wallpapers, and discolor paint. This ac-
tion is particularly severe if there is much moisture
in the air.

Liquid sulphur dioxide can be obtained in cyl-
inders and can be used for fumigation purposes if
desired. Two pounds of the liquid sulphur dioxide is
approximately equivalent to the gas produced from
burning 1 pound of sulphur. The use of sulphur di-
oxide is recommended only when other fumigants are
unavailable or for some reason cannot be used.


Naphthalene and Paradichlorobanzene

Woolens and furs, such as blankets, clothing,
fur-lined aviator's garments, helmets, and boots re-
quire protection constantly when in storage. The
most universally employed fumigants are the vapors of

Circular 22 Fumigation 41

naphthalene and paradichlorobenzene. The effect-
iveness of these vapors depends upon maintaining
them in sufficient concentration long enough to
either stupefy or kill the destructive insects.
Both chemicals can be depended upon when used in
thoroughly tight enclosures, but are not dependable
in open storage or loose containers which permit
the vapors to escape. Because heavier-than-air
vapors are formed by the evaporation of the crystals,
the supply of crystals must be replenished from time
to time, the frequency of retreatment depending upon
the ease with which the vapors can escape. From 2
to 4 pounds of crystals should be used to each 100
cubic feet of tight space. For prolonged storage,
the more rapidly evaporating and expensive paradi-
chlorobenzene has no advantage over flake naphtha-
lene in spite of its more agreeable odor. The odors
of both chemicals disappear from articles within a
few days after they have been ventilated thoroughly.

Clothing, blankets, and other susceptible
materials to be protected with naphthalene or para-
dichlorobenzene should be packed tightly in wooden
boxes well lined with heavy unbroken paper. Crystals
should be sifted between the layers of the commodity
as the packing proceeds. All stages of fabric pests
in supplies thus packed will be killed provided the
materials are tightly packed in a tight container.

An excellent method of employing naphthalene
is to construct tight rooms sufficiently large to
contain materials to be protected, and keep the air
of such rooms so impregnated with the vapors of naph-
thalene that the eyes and nose of a person entering
the room will sting. Such rooms are employed in the
warehousing industry for protection against fabric
pests. They are cheaply operated and readily worked,
and make it unnecessary to handle the supplies stored
therein when replenishment of the chemical is neces-
sary. The chemical is exposed about the edges of the
room, in trays if desired, but more often shoveled
about where it does not interfere with the workmen
during their brief stays in the room.

Circular 22 Fumigation 42

Ethylene Dichloride--Carbon Tetrachloride Hixture

When rooms stocked with naphthalene are not
desired, storage in tightly constructed rooms that
can be fumigated periodically with the ethiylene di-
chloride--carbon tetrachloride fumigating mixture
has found favor in the storage industry. Such rooms
are equipped with racks from which clothing can be
hung in catalogue order. Shallow trays suspended
from the ceiling provide for the evaporation of the
liquid fumigant either poured into them or pumped
into them from a container outside the room. All
large rooms are equipped with exhaust fans, and
other provisions for removing the fumigant after the
exposure period of 12 hours. The Haskelite !Manu-
facturing Corporation, Chicago, Illinois, has been
the only source of supply for the equipment of prac-
tically all fumigable storage rooms in use today.
The ethylene dichloride--carbon tetrachloride fumi-
gating mixture should be used at the rate of 14
pounds (about 5 quarts) per 1,000 cubic feet of
storage space. Fumigations of these storage rooms
are made as a matter of routine about once a month
during warm weather. Fumigable storage rooms are
usually supplemented with small receiving vaults of
about 500 cubic feet capacity in which materials
are first fumigated before being stored in larger

Ethylene Oxide--Carbon Dioxide Mixture

The ethylene oxide--carbon dioxide mixture, or
any other effective fumigant that will not damage
fabrics, can also be used in such storage rooms.
The ethylene oxide--carbon dioxide mixture should be
used at the rate of 15 pounds per 1,000 cubic feet
of space and can be applied from outside the storage
room through a simple piping system equipped with one
or more spray nozzles. The natural pressure of the
gas mixture in the cylinder will force it into the
room, If no piping system is available and the room

Circular 22 Fumigation 43

is large enough to require the entire contents of a
cylinder, the cylinder can be placed inside the room
and the contents discharged by opening the valve.
In such cases it is well to lash the cylinder to a
support, otherwise the pressure of the gas may over-
turn the cylinder when the valve is opened. If the
floors are varnished, painted or shellacked provi-
sion should be made to protect them from any liquid
that may drip from the cylinder.

Household furnishings, such as bedding, fur-
niture, rugs, etc. can also be fumigated in such
storage rooms or they can be treated in airtight
atmospheric fumigation vaults, such as are described
in the following pages.


For the treatment of small lots of food sup-
plies, animal feeds, household furnishings, garments,
fabrics, etc., gas-tight fumigation chambers or
vaults can be used to advantage. These can be con-
structed of any material that can be made gas-tight.
The most satisfactory are of concrete, brick, hollow
tile, or of wooden frame with a sheet metal lining.
The latter type is quite popular and can be con-
structed at low cost. The simplest form of construc-
tion of this type of vault consists of a frame work
of studding on the outside, with a lining of sheet
metal on the inside. The joints between the sheets
may be either welded or made tight with asphalt strips.
It is, of course, more desirable to reinforce the
metal lining on the outside with a layer of board
sheathing. Doors can be of the refrigerator type or
of the same type of construction as the walls of the
vault. A gasket of canvas-covered live rubber af-
fords a gas tight seal. A false floor should be pro-
vided, also an exhaust fan with a ventilating stack
leading outside the building housing the vault.
Vaults of brick or hollow tile should have a coating
of Keen's cement and one or two coats of paint on
the inside.

Circular 22 Fumigation 44

A plan for an ideal vault is shown in
figure 6. It can be made in any one of several
types of construction and is supplied with a fan for
either circulating the fumigant in the vault or ex-
hausting the vapors; tubing and spray nozzles for
introducing highly volatile fumigants; marine port
lights; thermometer; and a pilot light to indicate
when a fumigation is in progress.

Vault Fumigation Methods

The actual process of fumigation in a vault
is quite simple. The commodity to be treated is
loaded into the vault either by hand, or run in on
trucks or skids. The door is then closed and the
fumigant applied after which the vault is left locked
for the duration of the exposure. At the end of the
fumigation the exhaust fan is turned on and allowed
to run until the fumes not absorbed by the fumigated
commodity have been removed from the vault. While
the vault is being unloaded the exhaust fan should be
kept running for the protection of the workmen. In
some cases auxiliary fans may be required to supply
fresh air for the workmen, unless gas masks are worn,

The length of the exposure period will usually
depend upon circumstances. If there is no urgency a
24-hour exposure or even longer period should be al-
lowed, since the toxic action of a fumigant is in di-
rect proportion to the length of the exposure. In
the atmospheric fumigation of closely packed materials,
such as bagged milled cereals, penetration of the fu-
migant is slow.

The temperature of the commodity to be fumi-
gated is of vital importance. If the product is cold,
penetration by fumigants is greatly retarded, adsorp-
tion of the gas is increased and higher dosages are
required. It is doubtful whether it is practical to
fumigate products such as bagged milled cereals in
atmospheric vaults at temperatures below 70 F.

Circular 22 Fumigation 45


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Circular 22 Fumigation 46

Circulation of the fumigant in the vault by
means of a fan is advantageous. By use of a by-pass
the exhaust fan can be used for this purpose.

For applying the fumigant several different
methods can be used. Liquid fumigants tht are not
highly volatile are usually run in by graity or co-
pressed air into shallow evaporating pans ened
from the walls or ceiling. Volatile fuins, su
as liquid hydrocynic acid, methyl broide orthe
ethylene oxide-carbon dioxide :ixture are u y
introduced through a short piping systei t oe
or more spray nozzles, The natural pressure of a -
jority of these gases is sufficient to introduce he
dosage required. Hydrocyanic acid 1 as can be gene
rated for use in atmospheric vaults by any of the
methods described for warehouse fumigation.

The choice of the f:uigant will depend upon
its availability, cost, and suitability for treating
the product to be fumigated, except that methyl bro-
mide cannot be recommended for milled cereals or fatty
foods because they retain the bromine in deleterious
quantities. Leather goods also should not be fumi-
gated with methyl bromide. The quantity to be used
will depend on the length of exposure, the temperature
of the product, the nature of the product and the size
of the load in the vault. For practical purposes it
is convenient to base all dosage recommendations on
vaults filled to capacity.

Fumigation of Dry Staple Foods

It is not worthwhile to fumigate badly in-
fested flour or other milled cereals intended for
human consumption since they cannot be reconditioned
for food purposes by any practicable method. They
are not readily penetrated by hydrocyanic acid gas,
chloropicrin, or the ethylene oxide-carbon dioxide
mixture and are likely to retain injurious residues
if fumigated with methyl bromide. However, rice or
other grains, dry beans, dry peas, or dried fruit may
be fumigated successfully with any of these fumiants.

Circular 22 Fumigation 47

In general a dosage of from 1 to 2 pounds
of methyl bromide or hydrocyanic acid, 2 to 3 pounds
of chloropicrin or 20 to 30 pounds of the ethylene
oxide-carbon dioxide mixture per 1,000 cubic feet of
space will be required. An exposure period of 24
hours should be allowed.

Fumigation of Cured Meets and. Cheeses

Infestation of cured meets and cheeses by
mites, ham beetles, or skippers sometimes makes
fumigation necessary. Meat-storage houses that
are reasonably tight can usually be successfully fu-
migated with hydrocyanic acid at the rate of 1 pound
of liquid hydrocyanic acid or its equivalent per
1,000 cubic feet for a period of 24 hours. Such
treatment does not injure the meats, but if the in-
festation has penetrated deeply into the meat, it
is difficult to get a perfect kill. The 'ederal
meat-inspection regulations require that permission
for each fumigation of meat be obtained from the
Federal meat inspector.
Cheeses that are protected by an unbroken
layer of paraffin can be safely fumigated with hy-
drocyanic acid, but, owing to the danger of their
absorbing large quantities of the gas, unprotected
dhOeses should be removed from a warehouse that is
to be fumigated.

For the treatment of small quantities of cured
meats, or cheeses, a fumigation vault or other tight
container is recommended. Carbon disulphide at the
rate of 10 pounds, ethylene 6xide at the rate of 2
pounds, or the ettylene oxide-carbon dioxide mixture
at the rate of 20 pounds, per 1,000 cubic feet of
skace can be used for a period of 24 hours.

CirClar 22 Fiigation 48


If warehouses are too loosely constructed
and no atmospheric vaults are available, a rubber-
ized tarpaulin can be pressed into service to treat
individual stacks of supplies. At times it is in-
convenient to treat an entire warehouse and the
treatment of individual stacks is necessary. Canvas
tarpaulins, even those that have been treated to
make the waterproof, are not tight enough for this
purpose. Firms from which rubberized tarpaulins
can be obtained are listed at the end of this paper.

In figure 7 is shorn a pile of bagged seed
partially covered with a tarpaulin in preparation
for fumigation with methyl bromide. The bags are
arranged so that a space is forned at the top of the
pile to permit more rapid diffusion of the fumiganto
A piece of rubber tubing from the applicator conducts
the methyl bromide to the dame of the stack. Care
must be taken to weight down the edges of the tar-
paulin tightly to prevent loss of the gas.

Dosages and exposure periods are similar to
those used in tight vaults. In applying hydrocyanic
acid gas in tarpaulin fumigation the use of cans of
HCN discoids will be found convenient.

In fumigation under tarpaulins the seme pre-
cautions must be taken as with any other type of fu-
migation in which poisonous gases are used,. o one
must be allowed to remain in enclosures containing
stacks of commodities that are being fuigated under





Circular 22 Fumigation 50


Small supplies of grain stored in bins for
animal feeds that have become infested can be suc-
cessfully treated with the ethylene dichloride-
carbon tetrachloride mixture at the rate of 6 gallons,
or with carbon disulphide at the rate of 3 gallons,
per 1,000 bushels of grain. Both fumigants are ap-
plied by sprinkling them over the surface of the
grain in the bin. Small bins can be treated with the
aid of an ordinary sprinkling can. Owing to the fire
hazard connected with the use of carbon disulphide
this material should rarely be used and then only
when the bin to be treated is segregated from other
buildings and danger from fire can be controlled.

Small quantities of both of these materials
can be applied without the use of a gas mask, but
any extended use requires the wearing of one. Large
quantities of the ethylene dichloride-carbon tetra-
chloride mixture can be applied from outside large
bins with the aid of a bucket sprayer or a larger
power sprayer. It is dangerous to attempt to apply
carbon disulphide in this manner.


The accompanying list of concerns and their
products is included for the information of the users
of this circular, without given or inferred guarantee
of the reliability of the firms or endorsement of
their individual products. No attempt has been made
to make the list fully complete and no discrimination
is intended or implied against firms whose names or
products are not listed.

Circular 22 Fumigation 51

Calcium Cyanide

American Cyanamid & Chemical Corp., 30 Rockefeller
Plaza, New York, New York

Carbon Disulphide

Dow Chemical Company, Midland, Michigan
E. I. du Pont de Nemours & Company, Wilmington,
Mallinckrodt Chemical Works, 3600 North Second
Street, St. Louis, Miissouri
Stauffer Chemical Company, Inc., 420 Lexington
Avenue, New York, New York
Wheeler, Reynolds, & Stauffer, 624 California
Street, San Francisco, California

Carbon Tetrachloride

American Cyanamid & Chemical Corp., 30 Rockefeller
Plaza, New York, New York
J. T. Baker Chemical Company, North Phillipsburg,
New Jersey
Diamond Alkali Corp., 436 Seventh Avenue,
Pittsburgh, Pennsylvania
Dow Chemical Company, Midland, vichigan
Sonneborn Sons, Inc., 88 Lexington Avenue, New York,
New York


Innis, Speiden & Company, 117 Liberty Street,
New York, New York
Ansul Chemical Company, Miarinette, Wisconsin
Dow Chemical Company, Midland, Michigan

Ethylene Dichloride--Carbon Tetrachloride Mixture

Carbide & Carbon Chemicals Corp., 30 East 42nd Street,
New Xork, New York
Dow Chemical Company, Midland, Iichigan

Circular 22 -Fumigation 52

Ethylene Oxide--Carbon Dioxide Mixture

Carbide & Carbon Chemicals Corp., 30 East 42nd Street,
New York, New York

Gas Masks

Acme Protection Equipment Company, 3616 Liberty
Avenue., ittsburgh, Pennsylvania
E. D. Bullard Company, 275 Eighth Street, San
Francisco, California
Davis Emergency Equipment Company, 55 Van Dam Street,
New York, New York
Mine Safety Appliances Company, Braddock, Thomas
and Meade Streets, Pittsburgh, Pennsylvania
Willson Products Company, Inc., keading, Pennsylvania

Hydrocyanic Acid, Liquid

American Cyanamid & Chemical Corp., 30 Rockefeller
Plaza, New York, New York Kansas City,
Missouri Azusa, California

Hydrocyanic Acid, Discoids

American Cyanamid & Chemical Corp., 30 Rockefeller
Plaza, New York, New York Kansas City,
Missouri Azusa, California

Sodium Cyanide

American Cyanamid & Chemical Corp., see address above.
E. I. duPont de Nemours & Company, Inc., The R. & H.
Chemicals Department, Wilmington, Delaware -
Boston, Massachusetts Charlotte, North Caro-
lina Chicago, Illinois Kansas City,
Missouri New Orleans, Louisiana San Fran-
cisco, California
Hardy, Inc., Charles, 415 Lexington Avenue, New York,
New ork
Jungmann & rmpany, Inc., 157 Chambers Street, New
York, New York
Mallinckrodt Chemical Works, 3600 North Second Street,
St. Louis, Missouri

V- /

Circular 22 Fumigation 53

Sulphurio Acid

Most of the above films and many others. Probably
available locally.

Methyl Bromide

Dow Chemical Company, Mi-dland, Michigan New York
City St. Louis, Missouri Chicago, Illinois
E. I. du -Pont de Nemours Company, Inc., see address
Liquid Carbonic Corp., 3100 South Kedzie Avenue,
Chicago, Illinois

Rubberized Tarpaulins

Crawford Manufacturing Company, Inc., 3rd & Decatur
Streets, Richmond, Virginia
Pioneer Rubber Mills, 353 Sacramento Street,
San Francisco, California
Universal Rubber Manufacturing Company 958 Harrison
Street, San Francisco, California


Circular 22 Fumigation 54

Army, U. S. ------ 1937 -- Flour and Other Cereal
Products. Subsistence
Bull. 15, Q. M. Corps.
Back, E. A. and -- 1937 -- Industrial Fumigation
Cotton, R. T. Against Insects. U. S.
Dept. of Agr. Ciro. 369.
Back, E. A. and 1938 -- Stored Grain 4ests. U. So
Cotton, R. T. Dept. of Agr. Farmers'
Bull. 1260. Revised.
Back, B. A. ------ 1939 -- Weevils in Beans and Peas.
U. S. Dept. of Agr. Farmers'
Bull. 1275. MIevised.
Cotton, R. T. --- 1938 Control of Insects Attacking
Grain in Farm Storage.
U. S. Dept. of Agr.
Farmers' Bull. 1811.
Cotton, R. T. --- 1941 Insect Pests of stored Grain
and Grain Products, 242
pp. Burgess Publishing
Co., Minneapolis, Minn.
Cotton, R. T. -- 1941 Control of Insects in Ele-
vator Storage* U. S,
Dept. of Agr. Farmers,
Bull. 1880.
Dean, G. A., --- 1937 Flour Mill Insects and
Cotton, R. T., Their Control. U. S. Dept.
and Wagner, G. B. of Agr. Circ. 390.

Forbes, &. J. ---- 1937 Protection Against Mine Gases.
and Grove, G. W. U. S. Dept. of Interior,
SBur of Mines, Kiner's
Circ. 35, 52 pp., illus.

Circuar 22 Fumigation 55

Sayers R. R., ---- 1929 -- Physiological Response
Yant, P., attending Exposure to
Thomas, W. P. and Vapors of Methyl Bro-
Beyer, L. B. mide, Methyl Chloride,
Ethyl Bromide, Ethyl
Chloride. U. S. Public
Health Service Rept. 185.
Schren, H. H ---- 1941 -- List of Respiratory Pro-
tective Devices Approved
by the Bureau of kines.
U. S, Dept. of Interior,
Bureau of Mines Informa-
tion Circ. 7030 R, 9 PP.
ttderhill, F. P. 1919 The Physiology and Exper-
imental Treatment of
Pioisoning with the Le-
thal War Gas. Arch. Int.
Med. 23:753-770.
U. S. Public ------ 1938 -- Preliminary Recommendations
Health Service to Fumigators using Methyl
Bromide or Mixtures Con-
taining Methyl Bromide as
a Fumigant, U. S. Pub.
Health Service, Mat. Inst,
of Health, Div. of Ind.
Hygiene. Mimeographed
Leaflet dated May 16 1938.
War Department --- 1939 -- Army Baker. U. S. Training
Manual 2100-151.

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