SOME SCALE INSECTS. 89 



Scurfy barkloiise {Chionaspis furfurus), Fig. 3. 



West Indian peach scale (Diaspis lanatus), Fig. 4. 



Kose and blackberry scale (Dlaspis rosce), Fig. 5. 



Etionymus scale (^Chionasjyis euoni/mi), Fig. 6. 



Beech and Linden scale (Prosopophora sp.). 



"Willow scale (Chionaspis salicis). 



Imported oak barklonse {Asterodiaspiis qnercicola). 



Cottony maple barklouse {Tulvinaria inmLinerahilis). 



Maple leaf scale insect (Pseudococcus aceris). 



English walnut scale (^Aspidiotus juglans-regioi), Fig. 7. 



Rapacious scale (Aspidiotus cameUiw), "Fig. 8. 



Common plum Lecanium (Lecanium prunastri) . 



Remedies for Scale Insects. — Experimental work with 

 remedies for scale insects was begun by the Department of Agri- 

 culture in 1880, at a time when Professor Comstock made his 

 extensive investigation of the insects of this group. The recom- 

 mendations which he made at that time practically focussed upon 

 whale-oil soap. In California he found that this substance, ap- 

 plied at the rate of three-quarters of a pound to the gallon of 

 water and at a temperature of one hundred degrees Fahrenheit, 

 killed every individual of the red scale upon orange. Two years 

 later the remarkable work of ]Mr. H. G. Hubbard upon the scale 

 insects of the orange in Florida resulted in the systematizing of 

 the work with kerosene emulsions, and demonstrated that no 

 better mixtures can be applied to unprotected scale insects than 

 a solution of the standard kerosene soap emulsion in ten parts of 

 water. Mr. Hubbard's results were widely published, and his 

 mixture remained from that time until two years ago the generally 

 accepted and almost solely used remedy against scale insects. No 

 satisfactory experiments with winter washes were made in the 

 East until tlie winter of 1893-94. California workers had, in the 

 meantime, however, developed a line of washes based in the main 

 on lime, salt, and sulphur, or lime, sulphur, and blue vitriol, or 

 resin, caustic soda, and fish oil. In the winter of 189.3-94 exten- 

 sive experiments were begun at the Department of Agriculture in 

 Washington, and these California washes were naturally tested 

 at the start. It was found, somewhat to our surprise, that 

 although the evidence in favor of their efficacy on the Pacific 

 slope Avas not to be doubted, in the East they were practically of 

 no use. By no means all of the scales were killed, and in some 



