426 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
of this agent, who used a white powder, scattering this every place that 
the cockroaches frequented. This agent would not tell what the 
powder contained, nor would he sell it, insisting on doing the work him¬ 
self. The next morning after the powder was scattered on the shelves, 
floor and in all corners, the floor was literally covered with dead and 
dying roaches and within a week’s time scarcely any could be found, a 
few days later none at all. Very few roaches were found several weeks 
later but these may have come in afterwards. The writer scraped up 
some of this powder and turned it over to Dr. S. B. Kuzirian of the 
Chemical Section of the experiment station for analysis. His report 
shows that powdered boric acid was the only thing found. 
August 22 a mixture of powdered borax and powdered sugar was 
again tried in the kitchen of a sorority house. After three days no 
dead roaches could be found, although they were seen in the mixture 
and under papers where it was scattered. On August 25 this mixture 
was removed and powdered boric acid scattered on the shelves and 
floor. The next morning a number of dead roaches were seen and at 
the end of ten days only one live roach could be found. None at all 
were observed on later visits. Boric acid was again tried in the dis¬ 
pensary room of the bacteriology department of the college, with even 
better success. After four days only one roach could be found and none 
on later visits. 
At another time boric acid was tried on a larger scale in a large 
grocery store and basement. Although the work here was not done 
thoroughly enough to completely rid the place of roaches, yet their 
numbers were greatly reduced. So quickly and effectively did the boric 
acid work that twenty dead and dying roaches were picked up behind 
one fifteen foot counter half an hour after it was placed there. 
These tests showed the effectiveness of boric acid. Further trials 
were made to determine how the roaches obtained the material and also 
to determine further if powdered borax and powdered sugar would not 
work as effectively. More roaches were trapped and confined in bat¬ 
tery jars in the insectary in making further trials. 
On one occasion after boric acid had been used at the sorority house 
one healthy roach and one nearly dead were picked up and placed in 
the same jar. They were given no food and left undisturbed. One 
died later in the day but was not removed. Three days later the re¬ 
maining healthy roach ate the stomach and intestine of the dead one 
and died in a short time. 
This showed that cockroaches ate the boric acid and that, after 
killing one individual, the boric acid might still be fatal to others. To 
test this' point further five roaches, recently killed with boric acid, 
were thoroughly washed and the stomach and intestines removed and 
