October, ’18] 
WALTER: COCKROACH CONTROL 
427 
placed in a battery jar with six healthy roaches. Within four days all 
of the intestines had been eaten and four roaches had died. The two 
remaining were not affected, although retained in the jar fully a week 
longer. 
From this work it was seen that boric acid readily killed cockroaches 
upon eating it. Would they eat it more readily if mixed with powdered 
sugar? In another experiment eighteen roaches were placed in each of 
two battery jars and the powder placed at one side of the jar. No 
difference was observed in the effectiveness of boric acid used alone or 
mixed with sugar. The roaches were placed in the cages at 5.00 p. m. 
September 12 and by noon September 14 all were dead in both jars. 
Table No. 2. Boric Acid Alone Compared with Boric Acid and Powdered 
Sugar. 
Boric acid alone Boric acid and powdered sugar 
Sept. 12, 5 p. m. 
Experiment started 
Sept. 13, 8 a. m. 
7 dead 
7 dead 
12 noon 
5 dead 
3 dead 
4 p. m. 
1 dead 
2 dead 
Sept. 14, 8 a. m. 
4 dead 
5 dead 
12 noon 
1 dead 
1 dead 
Total 
18 dead 
18 dead 
Up to this time the powdered borax and powdered sugar mixture had 
been used by the writer only in the open and apparently without suc¬ 
cess. Thirty roaches were now placed in each of two jars. Borax 
and sugar were placed in one, boric acid in the other, each at one side of 
the jar. This was to determine whether the borax mixture would kill 
the roaches and also to determine the length of time required to kill all 
the roaches in each case. In this experiment all the roaches in the cage 
with the boric acid were dead after four days, while it required thirteen 
days to kill all of them with the borax. Sixteen roaches in the cage with 
the borax were dead at the end of four days. The sugar caused the 
mixture to become more compact, evidently retarding its action. No 
other food was given in either cage. 
A few days later the same experiment was repeated using thirty 
roaches in each cage as before, this time introducing a banana peeling, 
of which roaches are very fond, into each of the two cages. The 
powder was placed in a watch glass so that the roaches had free access to 
it, but need not necessarily get into it. In this case the boric acid killed 
all roaches in four days, while it took fourteen days to kill them with 
the borax. Dr. Geo. D. Shafer 1 has shown that borax also acts as a 
1 Technical Bulletin No. 21, Mich. Agr. Coll. Exp. Station, p. 54, 1915. 
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