12 



BULLETIN 707, U. S. DEPARTMENT OF AGRICULTURE. 



placed with a mixture of 50 per cent plaster of Paris and 50 per 

 cent flour, the roaches being allowed to remain on the table. Observa- 

 tions for 30 days showed that none had been killed, and they ap- 

 peared as lively and healthy as when placed on the table. The pres- 

 ence on the table of innumerable roach droppings in the form of elon- 

 gated white pellets of hardened plaster of Paris is conclusive evidence 

 that the mixture was freely eaten, but that the plaster of Paris did 

 not " set " until after it had left the intestines. 



These tests demonstrate that the " plaster of Paris and flour treat- 

 ment " is of no value against the common roach or "Croton bug," 

 and would throw grave doubts upon its effectiveness against any 

 other species of roaches. 



MISCELLANEOUS POWDERS PAETIALLY EFFECTIVE AGAINST COCKROACHES. 



Table III gives the results of tests with miscellaneous powders. 



Table III.— Results of tests with miscellaneous materials which were found to 

 be effective against roaches. 



Test 

 No. 



17 

 118 



2 19 



20 



21 



Active ingredients. 



Alum, 100 per cent 



Arsenious oxid, 8.98 per cent. 



Arsenious oxid, 61.01 per cent . . . . 



Arsenious oxid, 86.93 per cent 



Arsenious oxid, 76.14 per cent, 



and barium carbonate, 22.89 per 



cent, mixture. 

 Barium carbonate, 100 per cent... 



Barium fluorid, 100 per cent 



Do 



Boracic acid 



Calcium fluorid, 100 per cent 



Do 



Copper sulphate, 100 per cent 



Hellebore ( Veratrum sp.), 100 per 



cent. 

 Mercury bichlorid, 1.09 per cent.. 



Mercury bichlorid, 100 per cent. . . 



Mercury bichlorid, 5. 72 per cent, 

 and phenol, 1.44 per cent, mix- 

 ture. 



Paradichlorobenzene, 100 percent. 

 Do 



SabadUla seeds, powdered, 10 per 

 cent. 



Sodium silicofluorid, 100 per cent. 

 Do 



Inert ingredients. 



Sodium oxid and 



paper. 

 Sucrose, 35.28 per 



cent. 

 Talc, 13.07 per cent. . 

 do 



.do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 

 .do. 



Ethyl and methyl 

 alcohol. 



do 



Water 



.do. 

 .do. 



Com meal, 90 per 

 cent. 



do 



do 



Kmdof 



test. 



Cage. . 

 ...do... 



...do... 



..do... 

 ...do... 



..do... 

 ..do... 

 Room. , 

 ..do... 



Room. 

 Cage . . 

 ..do.. 



.do. 



.do., 

 -do.. 



..do... 

 Room. 

 Cage.. 



..do.., 

 Room. 



Number 

 used. 



40 



40 

 Many. 

 Many. 



20 

 Many. 



40 

 120 



140 



20 

 40 



100 

 Many. 



Duration 

 of test. 



Days. 



4-7 

 3 



3 



10-14 

 14 



7 

 7 

 14 



8 

 7-14 



1 



8-14 



2-7 



2 



19-34 



5-7 

 14 



Per cent 

 killed. 



60-80 

 60-80 



95-100 

 100 



100 



100 



98-100 



50-60 



95 



95 



80-90 



85-100 



30-65 



100 

 100 



100 



48 



70-100 



75-100 

 67 



> Fumigation. 



2 Furnished as food. 



All of the materials given in Table III were active in varying 

 degrees, killing from 48 to 100 per cent. 



Although it would appear that several of these materials were sat- 

 isfactorily effective, the fact that in the cage tests, in most cases, 

 they required from 4 to 14 days to kill all of the treated roaches in 



