Article II. — Recent Insecticide Experiments in Illinois with Lu- 

 bricating Oil Emulsions. By S. C. Chandler, W. P. Flint, and L. L. 



HUBER. 



Introduction 



From 1919 to 1922 inclusive, the San Jose scale caused more dam- 

 age in southern Illinois than in any equal period since it was first estab- 

 lished in this state. Following the work of Dr. Forbes and his assist- 

 ants in 1900, 1901, and 1902, liquid lime-sulfur had been considered 

 the standard remedy for San Jose scale control. Previous to 1919, it had 

 not failed to give a satisfactory commercial control where thoroughly 

 applied at dilutions of from 1 to 6, to 1 to 8. During 1920 and 1921, 

 some of the best and most careful orchardists in southern Illinois lost 

 trees from scale although these trees had been thoroughly sprayed with 

 lime sulfur. In some instances the failure to control with it could be 

 accounted for by the fact that the trees had been poorly sprayed, or 

 an insufficient amount of material had been applied. In other cases, 

 however, the applications had been made as thoroughly as seemed possible 

 and enough material had been put on to cover the trees thoroughly. 

 During the years mentioned above, a series of mild winters following 

 warm late falls had allowed J;he scale to increase at an unusual rate, 

 so that trees having a small amount of live scale remaining upon them 

 in spring were heavily infested by fall. Because of the failure of lime 

 sulfur to give a satisfactory control of scale, a series of experiments 

 to test other scalecides was made by the Natural History Survey during 

 the winter of 1922. 



These experiments were planned to give a comparison of com- 

 mercial liquid and dry lime-sulfur with commercial miscible oils and 

 homemade lubricating-'oil emulsions. The lubricating oil emulsion used, 

 was of the type developed by W. W. Yothers, of the United States 

 Bureau of Entomology for combating citrus scale insects in Florida, 

 and was made by boiling together: 



Potash-fish-oil soap 1 pound 



Water ^ gallon 



Light grade lubricating oil 1 gallon 



The mixture was boiled for about five minutes, removed from the fire, 

 and pumped twice under a pressure of about seventy-five pounds, and it 

 was then diluted at the rate of three gallons of the stock emulsion to 

 ninety-seven gallons of water. 



