EXPERIMENTS AGAINST BEDBUGS. 3 



stroying the eggs whenever they come in contact with them, and 

 here, also, their powers of penetration greatly increase their prac- 

 tical effectiveness. 



The preparations composed largely of oils of the nature of gaso- 

 line were found, in jar tests, to be as effective as the kerosene sprays, 

 but because of very rapid evaporation they are not as valuable under 

 practical conditions as are those composed of a heavier oil, and it 

 has been found that gasoline, at least under certain conditions, is 

 not effective against bedbug eggs. (See p. 7.) 



COAL-TAB CEEOSOTE EMULSIONS. 



Numerous tests with coal-tar creosote emulsions indicate roughly 

 that the effectiveness of this class of materials depends on two fac- 

 tors: (1) The dilution, and (2) the amount of water present in the 

 original emulsion. When used Undiluted, these emulsions killed from 

 95 to 100 per cent in 24 hours, but when diluted 1 to 30 or more, in 

 no case were all of the insects killed, although many of the tests 

 were continued for seven days. 



MEECUEIC CHLORID. 



Table I gives the results of tests with mercuric chlorid against 

 bedbugs. 



Table I. — Results of tests with mercuric chlorid used as spray against 

 bedbugs confined in jars. 



Test 

 No. 



Per cent 

 mercuric 

 chlorid. 



Other ingredients. 



Number 



Duration 



Per cent 



used. 



of test. 



dead. 





Days. 





40 



4 



10 



80 



8 



39 



120 



4-8 



20-53 



120 



5 



70 



65 



12 



75-100 



80 



8 



58 



80 



8 



77 



40 



6 



45-95 



40 



1 



100 



Un- 

 treated, 

 per cent 



dead. 



2 

 3 

 4 



5 

 5 



7 



0.23 

 .50 

 1.00 

 1.09 

 1.35 

 2.00 

 4.00 

 5.72 

 6.00 



Water 



....do 



do 



Alcohol 



Alum, salt, water 



Water 



....do 



Water, alcohol, phenol 1.44 per cent. 

 Water 



10 



15 



7.5 

 30 

 23 

 15 





 13 

 35 



Table I shows that mercuric chlorid, even in a 2 per cent solution, 

 is somewhat effective, and that a 6 per cent solution killed 100 per 

 cent of the treated bugs within 24 hours. 



As mercuric chlorid is a very violent poison, its use ordinarily 

 would be attended with considerable danger, but in solution a small 

 amount can be used effectively without serious danger of accidental 

 poisoning. In solution it also can be more thoroughly applied and 

 forced into cracks and holes, so that, on drying, it leaves a thin film 

 of poison which will remain to kill any bugs not hit by the spray. 



