October, ’18] 
WALTER: COCKROACH CONTROL 
429 
The habit of extreme personal cleanliness was observed shortly after 
the work was begun with roaches confined in cages. This interesting 
habit, also observed and recorded by Dr. L. 0. Howard 1 and Dr. Geo. 
D. Shafer 2 throws a great deal of light on the reason for roaches eating; 
boric acid. 
A cockroach covered with dust or dirt will, when unmolested, begin a 
process of cleaning. Usually it draws first one antenna after the other 
slowly between the mandibles, then begins on the legs, later the ab¬ 
domen, doubling up almost into a ball until it cleans itself thoroughly. 
Boric acid being a very fine, light powder, readily adheres to the roach 
and must be cleaned off. The powdered borax and powdered sugar 
mixture is heavier, and readily hardens if moisture is present, so does 
not stick as well. The writer has never observed roaches eating either 
the borax and sugar mixture or boric acid except in their efforts at 
cleanliness. Boric acid has no effect on the eggs already deposited so 
unless the powder is left on the shelves for a considerable time, treat¬ 
ment must be repeated after a few weeks. 
Prices for boric acid vary greatly at the local drug stores. This year 
(1917) it was purchased at 30 cents per pound. The New York whole¬ 
sale market report for November 20, 19 1 7 3 gave the price of powdered 
boric acid at 13| cents per pound. Sodium fluorid, which is also used 
to kill roaches, is quoted in the same Journal at 18 to 19 cents. Sodium 
fluorid was much higher in price than boric acid so was not used in this 
work. 
Summary 
1. Traps may be used as means of control but cannot be relied on as a 
method of extermination. 
2. Boric acid is a safe and economical material to use against the 
roaches as it is nonpoisonous to human beings and yet very effective 
against roaches. 
3. A mixture of equal parts of powdered borax and powdered sugar 
ground together is effective against cockroaches, is safe and economical,, 
although acting slower than boric acid. 
4. Cockroaches eat these substances in an effort to keep clean and 
not for any possible food value. 
1 The Insect Book, p. 331, 1902. 
2 Technical Bulletin No. 21, Mich. Agr. Coll. Exp. Station, p. 55, 1915. 
3 Journal of Industrial and Engineering Chemistry, December, 1917. 
