Insect-proofing cotton bags


Material Information

Insect-proofing cotton bags
Physical Description:
4 p. : ; 27 cm.
Cotton, R. T
Frankenfeld, J. C ( Justus Carl ), b. 1901
Strickland, Winston B
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:
Insect-resistant packaging   ( lcsh )
Cotton fabrics   ( lcsh )
Food storage pests -- Control   ( lcsh )
federal government publication   ( marcgt )
non-fiction   ( marcgt )


General Note:
Caption title.
General Note:
General Note:
"July 1949."
Statement of Responsibility:
by R.T. Cotton and Justus C. Frankenfeld and Winston B. Strickland.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030295356
oclc - 780190402
System ID:

Full Text

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July 1949 E-783

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


By Richard T. Cotton and Justus C. Frankenfeld, Division of Cereal and
Forage Insect Investigations, Bureau of Entomology and Plant Quar-
antine, and Winston B. Strickland, Southern Regional Research Lab-
oratory, Bureau of Agricultural and Industrial Chemistry.

Insect infestation of milled cereal products after they have been
bagged or packaged is a matter of great concern to manufacturers,
marketers, and consumers of such products. Insects readily enter
paper bags and fiber-board packages through small openings at the
point of closure, through needle holes in sewn bags, or by boring
directly through the paper or fiber board. The resistance of fabric
bags to insect entry depends on the kind of fabric. The coarser the
weave the more easily the fabric is penetrated. Adult insects may
thrust their ovipositors through the fabric and deposit their eggs in
the food material within, or the small larvae may crawl through needle
holes along the seams and at the top of the bags, or directly through the
meshs of the fabric.

Search for a Suitable Repellent

It was thought that the method of insect-proofing bags offering most
promise was impregnation of the material with a chemical repellent.
In 1940 tests were made with a number of repellents at the Manhattan,
Kans., laboratory of the Bureau of Entomology and Plant Quarantine.
Paper impregnated with a 1-500 nicotine solution or a 2-percent solu-
tion of sodium silicofluoride showed excellent resistance to penetration.
Both paper and cotton bags impregnated with various concentrations of
nicotine sulfate were tested, with varied effectiveness.
In experiments since 1940 many chemicals have been applied to
paper and fabric bags by dipping or by incorporation in sizing or coating
materials. Toxic materials such as DDT were found to give excellent
protection, but were not considered suitable for use with fabric bags
because it was difficult to combine them with the fabric in such a
manner that they would not contaminate the packed product. A repellent
that was nontoxic to warm-blooded animals appeared to be necessary.
In 1943 paper impregnated with pyrethrum extract was found to be an
excellent insect repellent.


In June 1946 various mixtures of pyrethrins with piperonyl butoxide
or piperonyl cyclohexanone were obtained for testing. Two formula-
tions--0.5 percent of pyrethrins plus 5 percent of piperonyl butoxide and
0.25 percent of pyrethrins plus 5 percent of piperonyl cyclohexanone--
both in deodorized kerosene with an emulsifier added, were used to
impregnate both paper and cotton bags. These formulations were used
both at full strength and in dilutions in water at 1 to 9 and 1 to 14
parts by volume. Both kinds of bags treated with these mixtures at
full strength gave excellent resistance to penetration for a long time.
Impregnated cotton oags filled with insect-free flour were exposed to
heavy infestation from July 1946 to July 1947. On examination the bag
treated with the pyrethrins-piperonyl butoxide formulation contained 2
dead flat grain beetles (Laemophlocus minutus (Oliv.)) and the bag
treated with the pyrethrins-piperonyl cyclohexanone formulation con-
tained 1 dead confused flour beetle (Trifolium confusum Duv.). An un-
treated bag contained 182 live flour beetles and 26 live flat grain beetles.
Baking tests conducted by the Milling Department of Kansas State College
in July 1946 showed no ill effect of the chemicals on the baking qualities
of flour packed and stored in the treated bags.

Development of Methods of Impregnating Bags

Tests with cotton bags were continued to determine minimum ef-
fective dosages and to perfect commercially practicable methods of
application. The material for the bags was prepared at the Southern
Regional Research Laboratory of the Bureau of Agricultural and Indus-
trial Chemistry, at New Orleans, La. Unbleached sheeting having 48 yarns
per inch in both warp and filling was impregnated with water dispersions
of a 1-10 pyrethrins-piperonyl butoxide mixture in connection with the
usual padding process, of such strengths that the finished cloth contained
5, 2.5, or 1.25 mg. of pyrethrins per square foot. To insure complete
and uniform penetration, a wetting agent of the sulfated fatty- alcohol
type was used, and the padding mixture was heated to boiling. The
treated cloth was then dried in a hot-air drier at 212 F. Bags 5 by 8
inches made from the treated cloths were filled with insect-free flour
and exposed to insect infestation for 8 months. Good protection was
obtained with bags treated at the highest dosage but not at the two lower
In another series of tests bags made from unbleached cotton cloth
treated with different dosages of 1-10 mixture of pyrethrins and pip-
eronyl butoxide and also with pyrethrins alone were filled with insect-
free flour and exposed for 7 months to continuous infestation by the


confused flour beetle, the cadelle (Tenebroides mauritanicus (L.)), and
the Mediterranean flour moth (gphestia kueluchniella Zell.). At the end of
the second, fourth, and seventh months the bags were examined and the
number of insects recorded, and the bags refilled with insect-free flour.
The data given in table 1 indicate that satisfactory protection against
these insects for a 7-month period was afforded by pyrethrins u ed
alone or in combination with piperonyl butoxide, at all the dosages

Table 1.--Resistance of cotton bags treated with various dosages of
pyrethrins, with and without piperonyl butoxide, to penetration by

Dosage of repellent Average number of insects
(milligrams per square foot Number per bag after--
of cloth) of bags
Pyrethrins i Piperonyl butoxide 12 months 4 months 7 months

10 100 4 1.75 0 0
7.5 75 4 1 1.25 0
5 50 4 0 .25 2
10 0 3 0 0 1
20 0 3 0 0 1
50 0 3 0 0 0.33
Untreated 1 60 60 443

The pyrethrins deteriorate rapidly when exposed to light. To de-
termine whether the repellency of treated cotton bags would also be
affected by exposure to light, bags made of cloth treated with the
1-10 pyrethrins-piperonyl butoxide formulation at the rate of 10 mg.
of pyrethrins per square foot were filled with insect-free flour and
exposed to insect infestation in darkness, in indirect light, and in
direct sunlight. When the flour was examined at the end of 7 months,
it was found that the insect repellency was retained under all con-
In the investigation of techniques for applying the repellent to
cotton cloth, the 1-10 pyrethrins-piperonyl butoxide formulation was
applied to warp yarn during the sizing operation. The sizing con-
sisted of 15 ounces of 40-fluidity thin boiling cornstarch per gallon
of water, cooked by boiling with an open steam line for 1 hour, to which
6 percent of emulsified beef tallow, based on the weight of the starch,
was then added. The insect repellent was also added after the starch
was cooked. The cooking of the starch and the sizing operation were


4- 3 1262 09239 2363

carried out in the laboratory under conditions similar to those in mill
practice. The sized warp was wound on a loom beam and woven into
sheeting 12 3/4 inches wide, with untreated filling. The cloth weighed
approximately 5 1/2 ounces per square yard, and contained 46 by 50
yarns per square inch. The dosages of the pyrethrins-piperonyl
butoxide mixture were such as to give 8 and 4 mg. of pyrethrins per
square foot. Identical cloth was woven for bags from yarns containing
no repellent. It should be emphasized that in the treated cloth only the
warp yarns contained the repellent. If both warp and filling had been
treated, the dosages would have been about twice as heavy. The cloth
was made into bags which were filled with insect-free flour and tested
over a 4-month period. At the end of this time no insects were found
in four replicate bags treated at the higher dosage, and only 1 insect
in one of the four bags treated at the lower dosage.
To test the persistence of the treatment on unfilled bags, treated
bags were stored for 5 months and then filled with flour and exposed
for 2 months to an extremely heavy infestation of Mediterranean flour
moths, confused flour beetles, cadelles, and lesser grain borers
(Rhyzopertha dominica (F.)). No insects penetrated any of the bags
that had been treated at either dosage, whereas untreated bags exposed
to the same infestation contained so many insects that it was impractical
to count them. During the test period insects were seldom seen on the
treated bags, whereas large numbers crawled over the untreated bags.
There was little mortality of flour beetles forced to remain on treated
cloth for long periods.


These experiments show that bags made from cotton that has been
treated with the extremely light dosages of pyrethrins, alone or mixed
with piperonyl butoxide, as discussed above, will protect flour packed
therein from insect infestation for at least 7 months. These chemicals
are of a comparatively low order of toxicity to warm-blooded animals,
and it seems unlikely that at the rates and methods of application used
in these experiments they will contaminate products packed in treated
bags. Further work is needed, however, to settle this question and to
determine the minimum effective dosages. Treated cloth is not
materially changed in appearance. Pyrethrins give it a slight though
not objectionable odor.
At present prices the cost of the treatment is low enough to make
commercial application practicable. Manufacturers of fabrics for
cotton bags may find it possible to treat warp yarns during sizing at
no additional cost other than that of the chemicals.