PREVENTIVE MEASURES 197 



icals used to destroy the larvae in the manure pile may 

 be roughly divided into two classes : ( i ) Contact poi- 

 sons, and (2) stomach poisons. To the first class be- 

 long such preparations as the kerosenes (generally 

 used in the form of emulsions) and the creosol prepa- 

 rations, also chloride of lime. To the second class be- 

 long the arsenicals, represented by arsenate of lead and 

 Paris green. All of these insecticides are more or less 

 effective when used in proper concentrations and in 

 sufficient quantities, but none of them can be applied 

 with any degree of safety to man or to the domesticated 

 animals because of either their inflammable, poisonous, 

 or corrosive nature." 



Prof. S. A. Forbes, of Illinois, also caused a series 

 of experiments of this sort to be carried on at the Illi- 

 nois State Experiment Station at Urbana. The work 

 was done under his direction by Mr. J. J. Davis. The 

 notes have not been published, but have been kindly 

 sent to the writer by Professor Forbes. In these ex- 

 periments it was found that three pounds of hydrated 

 high calcium lime of the Marblehead Lime Company, 

 mixed with fifteen pounds of horse manure, killed 

 ninety-four per cent, of the larvse; two pounds mixed 

 with twelve pounds of manure killed sixty-nine and 

 one-tenth per cent, of the larvse; four pounds with 

 twelve pounds of manure killed sixty-one and three- 

 tenths per cent. The diminished percentage in the 

 last two experiments is accounted for by the fact that 

 the larvse were nearly full-grown. 



An experiment with two pounds of iron sulphate 



