886 
Journdl of Agricultural Research 
Vol. XXXI, No. 9 
sene, fuel oil, crude petroleum, coal-tar dips, creosotes, and (turpen¬ 
tines were used in field tests. ' \ j 
These substances were first tested in very minute quantities on 
laboratory animals, many being diluted with light paraffine oil pr 
water. All that proved markedly toxic or irritating to the animal 
as the amounts used increased to a point that would kill the screw 
worms were eliminated. The remaining ones were then tested, jat 
first on small wounds, and, when no marked toxicity or irritation was 
observed, they were used on still larger wounds. The elimination 
process continued until only ethyl ether, benzene, toluene, xylene, 
chloroform, and carbon tetrachloride were used. 
Ethyl ether was considered too volatile for field use, and was elim¬ 
inated early for this reason. Toluene and xylene were about, las 
effective as benzene but were eliminated because they were less avail¬ 
able than benzene. Chloroform, chemicallv pure (not decomposed), 
was found to be quite satisfactory. Samples other than the chemi¬ 
cally pure product, however, were found to be objectionable for the 
same reasons as held for the decomposed chloroform. Carbon tetra¬ 
chloride and the chemically pure chloroform have a laxative effect 
on the wound that is undesirable. 
BENZENE AS A LARVICIDE 
Benzene has the same rank as a larvicide for the screw worm \as 
ethyl ether, chloroform, carbon tetrachloride, and xylene; the larvae 
in each case, when moistened with these materials, became inactive 
in an average of 40 seconds. In dry wounds, the time required to 
kill the larvae is practically the same for each and is about the same 
as that for the larvae moistened with the chemicals. Where the 
wounds do not have good drainage, the larvae are killed very slowly 
with benzene, ethyl ether, and xylene, as these materials float on the 
blood and serum, and it has been found that the larvae can live sub¬ 
merged in the wound from 20 to 30 minutes. Chloroform and car¬ 
bon tetrachloride sink into the blood and serum and mix with it, 
and all larvae are killed nearly as quickly as in a dry wound. To kill 
the larvae quickly with benzene in such wounds it is necessary to 
dry the wound first with cotton or a cloth and to apply the benzene 
immediately. 
EFFECT OF BENZENE ON WOUND 
Most wounds infested with screw worms have a considerable flow 
of fresh blood and serum. As long as the wound is dry it is not so 
attractive to the flies, and for this reason any chemical that has a 
tendency to laxate the wound is not desirable. Benzene acts as a 
styptic, and the blood flow stops in most cases as soon as all of the 
larvae are killed. When benzene is applied, and the wound takes on 
a dry, pale appearance, which lasts from 5 to 10 minutes or more, a 
wound dressing and fly repellent which adheres well to all parts should 
be applied, making a perfect coating which should continue the styptic 
effect. In no case has any indication of injury to the tissues been 
observed after an application of benzene, and the wound usually 
heals soft and dry without scabbing or cracking. On clean, smooth 
wounds there is hardly ever any dead tissue after treatment. 
