The use of DDT for roach control


Material Information

The use of DDT for roach control
Physical Description:
8 p. : ; 27 cm.
Henderson, L. S
United States -- Bureau of Entomology and Plant Quarantine
United States Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:


Subjects / Keywords:
DDT (Insecticide) -- Testing   ( lcsh )
Cockroaches -- Control   ( lcsh )
federal government publication   ( marcgt )
non-fiction   ( marcgt )


Additional Physical Form:
Also available in electronic format.
Statement of Responsibility:
by L.S. Henderson.
General Note:
Caption title.
General Note:
General Note:
"August 1946."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030292310
oclc - 780060593
System ID:

Full Text


United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine


By L. S. Henderson
Division of Insects Affecting ,.'an and Animals

ehon DDT first began to receive attention &s an insecticide,
there were reports that it might be satisfactory for the control of
the American roach but that it was not effective against the 2erman
roach, which is often called the water bug or croton bug This see-
ment has been passed along and repeated until at the present tira there
are many who believe that DDT is not effective agairst the Germ-i roach.

In early laboratory investigations DDT shoved definite promise of
being effective against all species of roaches that are troublesome in
homes. Tests were subsequently conducted under practical conditions in
several large institutions where there were extensive and heavy infesta-
tions of the German roach and where circumstances made control a
difficult matter. Effective control was obtained with either a 10-
percent DDT powder or a 5-percent solution of DDT in refined kerosene
In no case was there a failure. The armed forces have also found both
these preparations satisfactory for the control of roaches in ship
galleys, mess halls, barracks, hospitals, and other mili'. installations

The Research Committee of the Iational Pest Control Association,
in cooperation with the Bureau of Entomology and Plant Quarantine,
supervised extensive experiments with the 10-percent DDT dust and the
5-percent DDT solution for the control of all species of reaches infesting
homes. These materials were used by a large number of pest-control
operators in many cities in different sections of the country. All
the operators were given the same instructions for the use of the
insecticide under practical conditions just as it mi-it Ibe used in
normal service work. The operators made reports of th treatments and
of the results on standard forms.

In a very few cases unsatisfactory results were reported. In a
number of cases exceptionally good results were obtained. Lost of the
reports told of results somewhere between these two extremes, 2.e
general conclusion was that, on the basis of a single application,
the DDT powder or solution would be at least as effective as other
insecticides, including sodium fluoride and pyrethrum. Y'hen the uLT
powder was applied periodically, as is common practice in roach-control
work, it was superior to other materials. ,hen the 5-percent DDT
solution was used periodically in damp or moist areas, it was superior
to sodium fluoride or pyrethrum for the control of both German and
American roaches.

Individuals sometimes write that they have used several different
sprays and roach powders, including sodium fluoride and pyrethrum, in
the home and have not been able to control roaches. This often in-
dicates an unsatisfactory method of application rather than a fault
of the insecticide used. In such oases where common roach insecticides
have failed, it is not likely that DDT would give satisfactory results,
for DDT, like any other good insecticide, must be applied in the right
places and in the correct manner in order to be effective.

How DDT Affects Roaches

DDT affects the nervous system of the roach. The DDT is absorbed
through the feet or the body wall as the insect walks over the residue
or gets spray or powder onto the body. WVhen the DDT begins to take
effect, the insects become restless or excited, leave their hiding
places, and wander about for a time over the walls and ceiling. In
some cases this might be objectionable because the roaches may be
temporarily scattered all over the premises. This behavior, however,
is evidence that the insects are being affected by DDT and that they
will eventually die. After the initial period of excitement the
roaches begin to have tremors and violent convulsions, and will be
observed to shake and jump about. The next effect is the unco-
ordinated movement of the legs and later of the whole body. Finally
the roach kicks over on its 'ok, continuing to move its legs, but
gradually becoming weaker until death occurs.

When a proper application of DDT has been made, an infestation
may be pretty well cleaned out in 24 to 48 hours. If there are many
roaches in spots that have not been reached by the treatment,
eradication will take longer. Sometimes a week or more may elapse
before the infestation is eliminated.

DDT is not quick-acting against roaches, and death may not occur
for several days after contact with a DDT dust film or spray residue.
In laboratory experiments with tiny amounts of DDT, all the roaches
were on their backs and incapable of walking after 24 to 48 hours,
but they did not die until 5 to 7 days after the original contact
with DDT.

Although DDT does not cause rapid knock-down or immediate kill,
with the proper application it can be highly effective and give long-
lasting results. It is not necessary to treat every few days, as is
the case with some insecticides. Make one good application and then
let it work. The existing infestation will be eliminated and roaches
that appear after the premises have been treated will be killed when
they encounter the dust or spray deposit. An occasional dead roach

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will be evidence of this action. Roaches will not hide or develop in
treated areas. A single treatment will usually be effective for
several months. Subsequent treatments are necessary only when roaches
reappear. Small areas where the DDT deposit is destroyed by excessive
moisture, frequent cleaning, or other causes, may be given occasional
spot treatments when it is not necessary to make a general application
of insecticide.


In using DDT for roach control one should not expect immediate
kill by direct contact alone. To get the best results from DDT,
advantage should be taken of its long-lasting, or residual, property.
The habits of the roaches should be borne in mind and the insecticide
placed where the roaches hide or where they will walk through it
when they come out at night in search of food and water.

Dust.-- A powder should be used which contains 10 percent of DDT
in an inert carrier, such as pyrophyllite or talc. The powder can
best be applied with a small hand duster of the bellows, bulb, or
plunger type.

Many persons attempt to control roaches by placing a heavy band
of powder on the floor around the edges of the room. The powder is
left overnight or for a day or two and then swept up. AlthcuIh this
method may kill some roaches, it does not constitute an adequate
treatment because it does not reach the insects in their hiding places.
Many roaches may be able to go from their hiding places to sources
of food and water without crossing -'he band of powder. Then,too,
some powder preparations may be repellent to roaches and they will
tend to avoid the band of dust.

For a temporary treatment with ELT the powder should be applied
with a duster and distributed in a thin- film over the floor, aroed
the sink, over the top of worK. t-ls, or in other places where roaches
will walk. If an apartment or house is to be vacant, over a wea.k-
end or during a vacation period, t ut can be applied at the
beginning of the period and cwesr.- wr.en the occupants rtum,

Instead of such a temporary treatment it is better to make an
application that will be of more las.ting value by taking advntag. of
the residual property of DDT. The nozzle of the duster should be used
to blow the powder into cracks anrd crevices; behind and underneath
the splashboard and drainboard of Lh -.r,; in cupboard spaces,
especially in the upper corners; behind drawers and around drawer
spaces; around water pipes where they run along the wall or go through

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the wall; inside the compartment of mechanical refrigerators which
contains the motor and compressor; behind and underneath objects;
behind baseboards or moldine-; in cracks between the wall and window
or door frames; on the under side of tables or benches; ai-d in any
other hiding places, or where the roaches will run through the powder.
It is not necessary to use lar 'e amounts of powder, A light uniform
film will be sufficient. If larre numbers of roaches are present
and the infestation is distributed all over the room rather than in
isolated areas, it may be desirable to add the general dustinr,
described in the previous pa'-s _aph. The next day the powder in
exposed places can be cleaned up and that in secluded or concealed
spots left to continue its action. Such a general treatment will
probably not be necessary after the first application. Subsequent
treatments will usually be required only in those places where the
dust deposit has been destr-t by cleaning. or excessive moisture,
or where roaches make their appearance again.

Solution.- A 5--er-ent solution of DDT in deodorized kerosene
can be used to obtain a resi t in exposed places where the white
powder would be unsightly and i. jectionable. The solution will also
leave an effective residue on vertical surfaces, such as walls or the
sides of cupboards or cabinets, and on the under side of shelves,
tables, drawers, etc., to which a dust deposit would not adhere very
well. The residue frnrL the solution is not usually visible, and it
is not so easily removed cl-,ning and is less affected by moisture
than the dust deposit.

The solution can be applied lightly with a brush, but is more
readily put on with a sprayer. The spray should not be so fine that
a large amount of it floats off into space. The amount applied should
be sufficient to moisten the surface thoroughly, but not enough to
allow the liquid to stand up in droplets or run off. When the solution
is used, rather complete coverage is required to give satisfactory

Combination spray and dust treatment.- The combined use of a
5-percent DDT solution and *-7 -oerent LDT dust will often give more
satisfactory results than can be obtained with either form alone.
Each preparation should be applied in the places where it is most
suitable. The spray can be put on under surfaces, on vertical surfaces,
and in exposed places, and the dust can be blown into cracks and
crevices, or underneath and behind objects where it would be difficult
or impossible to apply a spray. The two forms should not be put on
so that they interfere with each other. That is, the dust should
not be blown onto a surface that is still wet with spray liquid,
and the solution should not be sprayed onto a dust deposit, lest
the latter become hardened or caked. Vhen that happens, the dust
deposit is not so effective as when it is in a loose, powdery condition.

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Emulsion.-- DDT emulsions have also given good roach control.
An emulsion my be used where it is desirable to avoid the fire hazar'.
or the temporary oily film of the kerosene solution. An emulsion is
formed by diluting with water a specially prepared concentrated solution
of DDT and an emulsifier. These concentrates usually contain 20 to
35 percent of DDT. To prepare a 5-percent DDT emulsion from a 25-
percent concentrate, use 1 part with 4 parts of water. For a 2.5-
percent emulsion use 1 part of concentrate to 9 parts of vater.
Starting with a 20-percent DDT concentrate, use 1 part with 3 parts
of water for a 5-percent emulsion or with 7 parts of water for a
2.5-percent emulsion. The emulsion should be applied to the same
places and in the same manner as an oil solution.

Suspension.- It has often been observed that a suspension of
DDT in water applied in a barn for fly control is also effective
against roaches. In some cases a concentration of only 1 or 2
percent of DDT has given satisfactory control. The suspension leaves
a visible white deposit, objectionable in some places, but in base-
ments or some other locations it would be of no consequence. A
suspension can be applied in damp areas where a powder treatment
would be adversely affected by moisture. A suspension is more
effective than a solution on porous or absorbent surfaces, such as
unpainted wood, plaster, or concrete. It also has the advantage over
a solution of having a water base, which gives freedom from fire
hazard, oily film, odor, and injury to the skin.

A suspension is prepared from a wettable DDT powder. This is a
specially prepared material in which other ingredients are added to
DDT so that it can be mixed with water. A satisfactory powder for
this purpose is one containing 50 percent of DDT. A 1-percent DDT
suspension is made by mixing 2.7 ounces (about 12 tablespoonfuls or
3/4 cupful) of a 50-percent powder with 1 gallon of water. For
larger quantities use 1 pound of 50-percent powder to each 6 gallons
of water. A 2- or 2.5-percent suspension should contain correspond-
ingly larger amounts of powder. It is difficult to handle suspensions
containing more than 2.5 percent of DDT.

Since the solid material in a suspension has a tendency to settle
slowly, the sprayer should be shaken frequently to insure a uniform
distribution of insecticide and prevent the particles from accumulating
in the bottom of the sprayer or clogging the nozzle. A suspension
may not be handled satisfactorily by some kinds of sprayers.

Household sprays containing some DDT.-- Many household sprays
contain 0.5 to 3 percent of DDT,together with some other toxic ingre-
dient. Such a spray may be excellent for direct contact action, but
the insects must be hit with the spray liquid if it is to be
effective. This type of spray should not be depended upon for a

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long-lasting residual action. For residual action five applications
of a 1-percent DDT spray are not so effective as one application of
a 5-percent solution.

Aerosols.-- Most gas-propelled aerosols from the so-called aerosol
"bombs' now available commercially contain small amounts of DDT and
pyrethrum as the insecticidal materials. These are designed primarily
as a means of distributing insecticides into the air of a room and
for uses similar to space sprays.

VWhen used in large amounts and directed into hiding places,
these aerosols are helpful in roach control. The amount of aerosol
used must be many times greater than that necessary to kill flying
insects. These high dosages may be irritating to humans and are not
considered desirable if people or pets remain in the room.

By using high dosa-es of aerosol, large numbers of roaches' may be
killed quickly and easily. Aerosols, however, have limited penetrat-
ing properties. Small amounts of aerosol may reaoh roaches in partially
protected places and disturb them so that they come into the open,
where they will be exposed to enough insecticide to kill them. Some
may move away, even into adjoining rooms. Still others in more pro-
tected places may not be reached by enough aerosol to disturb them
at all.

An aerosol application leaves little or no lasting effect and
repeated heavy applications are required to get satisfactory control.
A single application of DDT as a residual spray or dust will give
better results, especially vhen the infestation is well established,
or where the premises are subject to constant reinfestation.

Special Treatments for Different Species of Roaches

German roach.-- Most of the previous discussion with regard to
application has been made with reference to the German roach, which
is the species most frequently found in houses, restaurants, stores,
and institutions of various kinds. The German roach usually lives
and develops in the immediate area where it is troublesome, and the
control measures discussed will be effective in eliminating them.
In the home this species is usually found in the kitchen, and
sometimes in the bathroom.

American roach.-- This species will often be found developing
in large numbers in a warm, damp basement or storeroom. From there
they may spread, usually to the first floor o -the building. Control
measures applied where occasional roaches are found will kill those

individuals, but will not eP Lt.? -,ite the trouble and other roaches
will continue to come in. The insecticide be lied t the
source of the infestation, This I-,- often be in a damp plae -lere
a powder would absc:-'- moisture jrr'.i the air and --ome hardened or
glazed over the surface. VWhen this happens it is less effective than
when it is in a dry, du.t- condition so that the insects t i onto
their bodies when '-is walk .: it. I such ares it Il
better to use a solution, envision, or sus- esion, ratr n han a dust,
Where the white deposit of the suspension wil not be objecti --. e
this may be the best form to use,

Oriental roach,-- This species is even more limited to ap
areas than is the c....oan roach, and the me mthods of controlan
be applied.

Brown-banded roach,-- This species, sometimes called t
tropical roach, is 1-^.-- increasing o., -'-valent in the ted
States. In the home it may be found scattered all over the entire
house. It lives in high places in the room more o :'. than does the
German roach, which it scune'vhat resembles in size Fri. ap- -ao-nce
Small groups may' a6. **:.r in the upper parts of cupboards, on selves
in closets, or on book shelves, It will also be fo.i... in desk,
sewing-machine cabinets, radio cabinets, magazine racks, and
upholstered furniture, or on the under side of tables and chairs,
Egg capsules will be stuck to surfaces, usually in protected places
near where the insects are hiding.

This roach is often the most difficult species to control,
because of its habit of living all over the house. The hid'.- places
should be carefully sou-ht out and treated as directed in the section
discussing the combination spray and dust treatment. If this treat-
ment is applied extensively and thoroughly to hidin-, places and to
surfaces where the roaches will crawl over the residue, satisfactr:-
control or corr.flete eradication can be obtained, A small :._nt brush
is convenient and satisfac.tory for applyin. the 5--"rcent DJT solution
to some of the places Lcat should be tr'&:ted for the control of the
brown-banded roach.

Toxicity of DDT and Freeautions in Its Use

DDT is toxic to man, but the experience of workers in the bureauu
and its extensive use in Army mess halls have shown that it can be
used with safety as a household insecticide if it is properly labeled,
if it is applied as recommended, and if normal precautions are followed
as recommended here. On the basis of experimental work on animals,
the Food and Drug Administration and the National Institute of Health


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3 1262 09238 7256
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have stated that DDT is less toxic than sodium fluoride, which has
commonly been used as a roach poison, and, moreover, that DDT is not
a caustic poison or a primary irritant, and probably not a sensitiz-
ing agent.

Breathing of large amounts of fine spray mist from a 5-percent
DDT solution should be avoided. During the course of an ordinary
home treatment the kerosene and other solvents used with DDT could
cause headache or nausea if breathed for several hours. There will
be little risk involved if the rroper type of sprayer is used.

Excessive or repeated exposure of the skin to an oil solution of
DDT should be avoided. If spilled on the hands, it should be washed
off with soap and warm water, and the hands should be washed when
spraying is completed. The same precautions should be observed in
handling the concentrate from which emulsions are made. The spray
emulsion itself is less dangerous.

There is little to be feared in handling the dust, a water
suspension, or dry deposit left on treated surfaces v hen the spray
liquid has evaporated.

As is the case vw-ith all oil sprays, including the ordinary
household fly spray, the spray mist of the DDT-oil solution should
not be exposed to open flames or heated surfaces.

Containers of DDT insecticides should be kept out of the reach
of children, and DDT dusts should be plainly labeled to prevent their
being mistaken for flour, baking powder, powdered sugar, or some
other food material.

VThile the treatment is being made, foods, dishes, silverware, and
kitchen utensils should be covered or removed to prevent contamination.
Unprotected foods should not be placed on shelves recently treated
with a dust or spray. Packaged foods can be replaced in sprayed .
cupboards, cabinets, or drawers as soon as the spray has dried. This
will often take 3 or 4 hours.