14 BULLETIN 707, U. S. DEPARTMENT OF AGRICULTURE. 



Miscellaneous powders ineffective against cockroaches — Continued. 



Magnesium oxid (room). Silica (room). 



Pepper, cayenne (cage). Sodium bicarbonate (cage and room). 



Potato starch (room). Sodium carbonate (cage and room). 



Quassia (cage and room). Sulphur, refined (room). 



Road dust (cage and room). Sulphur sublimated (cage and room). 



Rosin (cage). Wheat flour (room). 



EXPERIMENTS WITH LIQUIDS AND PASTES. 



KILLING EFFECT OF PHOSPHORUS PASTES. 



Ten phosphorus pastes (proprietary), ranging from 0.14 per cent 

 to 2.33 per cent, were tested against roaches in cages, but none of 

 them proved effective. Several of them did kill from 50 to 90 per 

 cent, but since, in most cases, the tests were continued for at least 

 seven days, and in no case were all roaches killed in this time, it can 

 be seen that these pastes, even under the most severe conditions and 

 when no other food was available, were not effective to the extent 

 that would be considered satisfactory. 



In addition to the cage tests, two of the pastes were tested in 

 badly infested kitchens, and were still less effective. A few dead 

 roaches were found in the kitchens 24 hours after the application of 

 the pastes, but in no case did it appear that more than 10 per ,cent 

 had been killed, nor was the infestation greatly reduced. The pastes 

 used in the kitchen tests, however, contained only J. 01 per cent and 

 1.34 per cent of phosphorus. 



Under certain conditions, where all food can be kept from the 

 roaches for several days and the phosphorus paste used liberally, it 

 may give satisfaction. The senior writer observed the use of phos- 

 phorus paste against roaches, which, in the absence of other food, 

 fed on certain of the young, tender plants in a greenhouse of the 

 \Yar Department. Two or three roaches were seen eating the paste, 

 and the manager of the greenhouse claimed to get entirely satisfac- 

 tory results from the use of this substance against this insect. This 

 material, however, can not be relied upon for general use under aver- 

 age conditions. 



HYDROCARBON OILS. 



Numerous hydrocarbon-oil preparations, consisting essentially of 

 oils of the nature of gasoline or kerosene, or some heavier oil, to 

 which, in certain cases, had been added small amounts of nitro- 

 benzene or phenols, were tested against roaches in cages. All of 

 these sprays were found to be effective. 



In considering the effectiveness of these oil sprays, due weight must 

 be given to the fact that in cage tests the roaches are placed in the 



