460 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



The detailed reports on remedies just referred to show that kero- 

 sene emulsions must still be placed at the head of the list, not only 

 for ordinary scale-insects, but for this Icerya, so far as efttcacy is con- 

 cerned, though other remedies have the advantage of bein,., cheaper. 

 In the proportion of 1 part of the soap emulsion to 15 i^arts of water 

 it proves a perfect remedy for their Red Scale {Aspidiotus aurantii), 

 a species which has done incalculable damage in Australia and has 

 created much alarm in California, After a thorough application of 

 thf mixture in March Mr, Coquillett found that every scale-insect 

 was killed, and at the expiration of two months all had dropped from 

 the leaves. Used in the same proportion on the Cottony Cushion- 

 scale, however, it does not kill the old females with the egg-masses, 

 nor all of the eggs. Used at twice this strength it kills all of the eggs, 

 as well as the old females, and even when properly used at the rate of 

 1 part of the emulsion to 5 parts of water it leaves the tree uninjured, 



Mr, Coquillett reports, with reference to the much-praised caustic 

 soda, that it has no eifect on the eggs of the Icet-ya, even when ap- 

 plied so strong as to burn the bark brown and kill all the leaves. 

 Similarly, whale-oil soap, one pound to two gallons of water, does not 

 kill the eggs directly, nor does hard soap and water in the same pro- 

 portions, although the effect of the latter seems greater than that of 

 the former. They both, however, harden the egg-masses so that a large 

 proportion of the young larvae are unable to escape. The experiments 

 add greatly to the value of ordinary tobacco, for one of the most effect- 

 ual washes used is made by boiling one pound of tobacco leaves in one 

 gallon of water until the strength has been extracted from the leaves, 

 and then adding enough water to make two gallons. This wash, 

 however, costs about 5 cents per gallon, and is too expensive for ordi- 

 nary use. Mr. Koebele, experimenting through August, September, 

 and October, found that kerosene emulsified with soft-soap penetrates 

 the egg-sacs well, kills the old scales, and leaves the tree uninjured. 

 Emulsions of crude petroleum, although much cheaper, he found very 

 apt to injure the trees. He devoted his chief attention, on account of 

 their great cheapness, to the preparation of soaps and resin com- 

 pounds. He succeeded in making a number of these mixtures, which, 

 when properly diluted, need not cost more than from one-third to 

 one-half of a cent per gallon, and which, if thoroughly applied, will 

 bring about very satisfactory results, killing the insects and either 

 penetrating or hardening the egg-masses so as to preA^ent the hatch- 

 ing of the young. I am strongly of the opinion that the value of the 

 soap washes depends somewhat on the season of their application, 

 and that the greater success of Mr. Koebele v*^ith them as compared 

 with that of Mr. Coquillett was probably due to the fact that his ex- 

 j)eriments were made during the dry or rainless season. 



In connection with the subject of kerosene emulsions, I may put on 

 record here an important discovery made last spring in carrying on 

 further experiments at the office in emulsifying this oil. It is that 

 the white of eggs with a little sugar may be used as a satisfactory 

 substitute for milk where this is not accessible. 



If the white of 2 eggs, about 3 tablespoonfuls of sugar, f quart of 

 water, and 1^ quarts of kerosene are worked through a force-pump 

 and cyclone-nozzle for from 5 to 10 minutes a cream-like emulsion 

 is produced, which can be diluted with water to any desired amount 

 without any separation of the oil; provided that the emulsion is not 

 allowed to stand for any length of time. 

 Another investigation that has occupied considerable of my time 



