874 EXPERIMENT STATION RECORD. 



insect slightly resembles in its life history the codling moth, and it is recommended 

 that coffee plants be sprayed with Paris green, beginning with the first application 

 about 20 days after flowering. One application is usually not sufficient. 



The caprification of figs, K. Sa.i6 {Prometheus, 13 {1901), Nos. 622, pp. 788-792; 

 623, pp. 807-811; 624, PP- 823-827 , figs. 11).— In this article the author gives a gen- 

 eral account of the agency of the fig insect in the fertilization of Smyrna figs. The 

 discussion is based partly on publications of this Department. 



Experiments in the destruction of Diaspidse injurious to fruit trees, P. 

 Marshal (.hiJi. Inst. Nat. Agron., 24 {1897-1900), No. 16, pp. .587-598).— The species 

 of scales upon which these experiments were made were AspkUolus ostreu'formis and 

 Diaspis piricola. Experiments with undiluted kerosene were made under a number 

 of conditions. On February 26, 5 apple trees were sprinkled with kerosene. All of 

 the scales were destroyed and no injury was done to the trees. On March 25 plum, 

 apple, and pear trees were sprinkled with crude petroleum. The trees were not infested 

 with scales and the experiment was made for the purpose of determining the effect 

 of the oil on the trees. The trees were in bloom at the time of the experiment. No 

 injury was done to the trees except to the inflorescence of the pears. The flowers of 

 the apple appeared not to be injured. Similar experiments were made on other 

 trees, with like results. In one experiment made on April 9 the leaves of apples were 

 somewhat burned by the use of pure kerosene. An experiment with Russian oil of 

 naphtha, which was applied to pear and plum trees on March 25, showed that this 

 substance was very injurious to the trees. A kerosene emulsion was used in the fol- 

 lowing proportions: Boiling water 1,500 parts, black soap 400 parts, petroleum 1,000 

 parts. This mixture was sprayed on apple trees on April 9, with the result that 

 nearly all of the scales were killed and only a few of the apple blossoms were injured. 

 Crude vaselin diluted with kerosene was sprinkled upon apple trees on April 8. It 

 formed a thick and persistent coat on the trees and killed ail the scales, but greatly 

 injured the tree. An experiment with pure oil of sesame showed that this substance, 

 while destructive to the scales, was very injurious to vegetation. An emulsion of oil 

 of sesame and kerosene was made in the following proportions: Black soap 200 parts, 

 water 600 parts, oil of sesame 150 parts, and kerosene 100 parts. This mixture was 

 sprinkled on apple trees on Ajiril 8. All of the scales were destroyed and little injury 

 was done to the trees. Experiments were made with mixtures containing heavy oil 

 of coal tar. One mixture was prepared in the following proportions: Water 1,500 

 parts, heavy oil of coal tar 900 parts, black soap 400 parts. Pear trees sprayed with 

 this mixture diluted in 6 parts of water, on April 22, were uninjured, but the mixture 

 had no effect upon the scales. Similar negative results were obtained from a mixture 

 prepared as follows: Heavy oil of coal tar 1 kg., brown naphthalene 1 kg., quicklime 

 6 kg., and water 25 kg. Another mixture was prepared in the following manner: 

 Heavy oil of coal tar 1 cc, brown naphthalene 1 cc, quicklime 6 cc, water 20 cc, 

 black soap 50 gm. A considerable proportion of the scales were destroyed by this 

 mixture and vegetation was uninjured. An experiment with black soap mixed with 

 water in the proportion of 250 gm. of soap to 500 gm. of water showed that this sub- 

 stance caused no injury to the trees and destroyed a considerable proportion of the 

 scales. Pure pyroligneous acid was sprinkled on apple trees on April 1 ; nearly all of 

 the scales were killed and the tree was not seriously affected. Several experiments 

 with hot water were also conducted by the author. It is considered that kerosene 

 a«d crude petroleum are the most efficient insecticides in the destruction of scale 

 insects, and do not seriously injure apple or pear trees, even in bloom. Heat is effect- 

 ive in the destruction of scales, if the superficial parts of the trees can be brought to 

 a temperature of 60 to 65° C, but the difficulty of applying water to all parts of the 

 tree at this temperature is so great that this method for the destruction of scales is 

 practically impossible. 



