Value of Arsenic as an Addition to Kerosene Emulsion. 203 



Two experiments were made at Berkeley on the woolly Aphis, in conjunc- 

 tion with Messrs. Klee and McLennan. One and three parts of the com- 

 pound were used to eight of water. Owing to imperfect spraying only the 

 last did eflfective work. The leaves of the trees were falling at the time of 

 spraying, and the effect of the solution, especially on trees where three to 

 eight parts of wash were applied, was very noticeable, as the first tree lost 

 about half, while the second lost nearly all its leaves. On my visit to the 

 place a month later, however, there was little difference in the trees treated 

 and others infested with woolly Aphis, for those also began to lose their leaves 

 about two weeks after, as I was informed by Mr. McLennan, the gardener, 

 who is a very careful observer. Mr. Klee recommends this wash in the pro- 

 portion of one and one-half pints compound to one gallon of water. 



I have made numerous other experiments, and always had complete 

 success in killing this insect with one part compound to eight parts of water. 

 With this proportion, also, those on roots which were reached were killed. 

 I would recommend the same, viz. : one part of the compound to six parts 

 of water, on woolly Aphis. On the other hand, the plum Aphis, cabbage 

 Aphis, etc., are much easier to kill. Only one part of compound to eight of 

 water was used in experiments at Berkeley (August 10) on plum Aphis, and 

 none were living on examination August 17. At this strength the Aphis 

 will die instantly, and will not be able to move a leg if once wet. I have 

 killed them successfully even with a wash as low as one part of the com- 

 pound to sixteen parts of water, and would recommend one part of the com- 

 pound to twelve parts of water for plum Aphis, Aphis on rose, etc. At this 

 strength it may be safely used on any garden, and even on the most tender 

 hot-house plants, without the slightest injury to the plants themselves. It 

 should be used somewhat stronger on the cabbage Aphis. One part of the 

 compound to eight parts of water will be found effectual. At this strength 

 it was found that the larvse of Syrphus flies were not injured by wash, nor 

 were the parasites of the infested Aphis in any way affected, providing the 

 skin of the Aphis was dry when sprayed. 



A lot of house-flies (Musca domestica) which had concentrated out of 

 doors were sprayed with this solution, and died almost instantly. A large 

 flesh-fly (Sarcophaga) thrown into a weak solution, one to sixteen, taken out 

 and set on board, never moved its legs again. Fifteen minutes after, slight 

 convulsive movements were noticed on under side of body, and soon after 

 all life was extinct. A codling moth {Carpocapsa pomonella) sprayed with a 

 solution of one to eight was dead in nine minutes. Cut-worms (larvae of 

 Agrotis saucia) dipped in this mixture were not affected. 



It will be of interest to note that while in Los Angeles in April, 1887, 

 the following labels on trees treated for red scale {A. aurantii) were still 

 present: "Experiments wiih resin soap, 127, 147 and 149." All those trees 

 were free from red scale and L. olese, but full of Icerya. " Experiments with 

 resin compound, 133 and 156." No red scales could be found on these trees, 

 but L. olex were numerous on tree of experiment 133. Both trees were 

 badly infected with Icerya. 



