12 FARMERS’ BULLETIN 658, 
REMEDIES. 
Like the crows among birds, the roaches among insects are appar- 
ently unusually well endowed with the ability to guard themselves 
against enemies, displaying great intelligence in keeping out of the 
way of the irate housekeeper and in avoiding food or other substances 
which have been doctored with poison for their benefit. Their 
keenness in this direction may be the accumulated inheritance of 
many centuries during which the hand of man has ever been raised 
against them. Roaches may be controlled by the use of (1) poisons 
and repellents; (2) fumigants; and (3) trapping. 
POISONS AND REPELLENTS. 
As just noted, roaches often seem to display a knowledge of the 
presence of poisons in food, and, notwithstanding their practically 
omnivorous habits, a very little arsenic in baits seems to be readily 
detected by them. In attempting to eradicate roaches from the 
department storerooms where cloth-bound books are kept various 
paste mixtures containing arsenic were tried, but the roaches invari- 
ably refused to feed on them in the least. This applies particularly 
to the German roach, or Croton bug, and may not hold so strongly 
with the less wary and perhaps less intelligent larger roaches. 
Sodium fluorid.—One of the most effective simple means of ridding 
premises of roaches is dusting with commercial sodium fluorid, either 
pure or diluted one-half with some inert substance such as powdered 
gypsum or flour. Numerous practical tests conducted in lunch rooms, 
bakeries, milk-bottle exchanges, etc., in Washington by Messrs. E. W. 
Scott, W. S. Abbott, and W. H. Sill, working under the direction of 
Mr. A. L. Quaintance, of the Bureau of Entomology of this depart- 
ment, have shown that with the use of this substance roaches can be 
completely exterminated with very little trouble and cost and with 
none of the possible dangers which attend the use of hydrocyanic-acid 
gas, another efficient control method referred to below under the 
subject of fumigation. With the use of some dust gun or blower the 
sodium fluorid can be thoroughly dusted over the shelves, tables, 
floors, and the runways and hiding places of the roaches. The imme- 
diate effect is to cause these insects to come out of their retreats and 
rush about more or less blindly, showing evidence of discomfort, to 
be eventually followed in the course of a few hours by their death. 
These dead or paralyzed roaches can be swept up and burned, and 
complete extermination is effected within 24 hours. It is not defi- 
nitely known whether the sodium fluorid acts as a contact insecticide 
through the breathing pores or as a stomach poison. Probably, how- 
ever, it acts in both ways, inasmuch as it has been found to kill cater- 
pillars fed on foliage dusted with this substance. 
