APPEI¥DIX II. 



EXPERIMENTS WITH INSECTICIDES. 



[In part a reprint of matter published in the Report of the Entomologist, Annual Re- 

 port of the Commissioner of Agriculture for 1881-'82. pp. 1'20-1'26. ] 



Table I.— Kerosene emulsions. 



In Table I are given the results of seventeen experiments with kerosene in milk 

 emulsions of varying strength. When the percentage of Coccids killed is given, this 

 was obtained by cutting twigs, leaves, and portions of infested bark from all parts of 

 the tree, and examining microscopically in the laboratory large numbers of the scales 

 upo nthem. Under the head of young Coccids are iuclnded all those which have 

 well-formed, scales but have not begun to lay eggs. The youngest Bark-lice, or 

 those which have not yet molted, were almost invariably killed, and are not included 

 in the enumeration. 



The percentage of young Coccids killed, is given separately, including under this 

 head all ages between the formation of the permanent scale and the appearance of 

 eggs, but no larv£B before the first molt ; the latter were in nearly every case all killed. 

 Of scales which contained eggs three classes were examined and the percentage of 

 each obtained : (1) Scales in which a portion only of the eggs were destroyed; (2) 

 Scales in which all the eggs were killed ; (3) Scales in which no eggs were killed. 



Purple Scales (Mytilaspis ciiricola) were not abundant, but appear to be somewhat 

 less readily destroyed than Long Scale. All the experiments were made upon young 

 orange trees from three to six years old. An Aquapult pump of medium size was 

 used, and in each case the trees were sprayed from the ground and on four sides. 

 "Where the trees were more than eight or teu feet in height the upper branches did 

 not receive the spray with sufficient force, and show in some cases a. smaller percent- 

 age of Bark-lice destroyed than the lower portions of the same tree. For full-grown 

 trees a larger pump is needed, and the apparatus should be placed in a cart or other- 

 wise raised above the ground when used. 



The emulsions used were made as follows : 



No. 2. Kerosene, 1 pint ; sour cow's milk, 2 fluid ounces, dashed with a ladle ; 2 

 drachms of powdered chalk were first added to the milk, and 2 ounces water during 

 the stirring. 



An imperfect emulsion, not readily suspended in water. 



No. 3. Kerosene, 1 quart ; solution of condensed milk, 3 parts ; water, 5 parts, 12 

 fluid ounces. 



Emulsion made by spraying through the Aquapult pump and back into the pail. 

 Stable, and readilj' suspended in water. 



No. y. Kerosene, 1 quart ; condensed, milk, 12 fluid ounces, diluted with water, 36 

 ounces; emulsified with the Aquapult. 



No. 10. Kerosene, 25. G fluid ounces; condensed milk, 4.8 fluid ounces; water, 14.4 

 ounces; emulsified with pump. 



No. 11. Kerosene, 2 quarts; condensed milk, 12 fluid ounces (1 can); water, 20 

 ounces ; with pump. 



No. 13. Kerosene, 2 quarts, 4 fluid ounces ; condensed milk, 12 fluid ounces ; water, 

 24 ounces; with pump. 



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