UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 838 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



June 5. 1920 



CYPRESS BARK SCALE. 1 



By P. B. Herbert, 

 Scientific Assistant, Forest Insect Investigations. 



CONTENTS. 



Economic importance 



History i — 



Native host plant 



Distribution and spread- 

 Injury 



Associated insects 



Food plants 



Page. 



1 



Descriptions 



Life history and habits 



Seasonal history 



Predacious and parasitic enemies- 

 Control experiments 



Recommendations for control 



Summary 



Page. 



8 



12 



16 



18 

 19 

 20 

 22 



ECONOMIC IMPORTANCE. 



The Monterey cypress (Cupressus macrocarpa Hartw.) is one of 

 the most popular shade and ornamental trees in California. It is 

 planted separately or in hedgerows and often trimmed to formal 

 shapes. Due to its thick, spreading habits it makes a good wind- 

 break where it is planted in exposed areas. It is used especially 

 along the coast and in the sandy citrus areas of San Bernardino 

 Count}'. It is also cultivated as an ornamental tree in many other 

 parts of the world. 



The cypress bark scale infests a large percentage of these trees in 

 California, causing a great deal of injury, particularly to the 

 thickly planted hedgerows (PI. I, figs. 1, 2) and windbreaks. In the 

 San Francisco Bay region it ranks first among the pests of the 



1 Ehrhomia cupressi (Ehrhorn). Order Hemiptera, suborder Homoptera, family Coc- 

 cidae. 



Note. — An investigation of the injury to cypress trees in California was taken up by 

 the writer, at the suggestion of Dr. A. D. Hopkins, Forest Entomologist, in November, 

 1916. An examination made of these trees in the vicinity of the Los Gatos laboratory 

 disclosed the main cause of the injury to be the cypress bark scale, Ehrhomia cupressi 

 (Ehrhorn). This bulletin contains a record of studies of its history, biology, importance, 

 and control made during this investigation. 



The writer wishes to acknowledge the assistance of Dr. A. D. Hopkins, Forest Ento- 

 mologist ; Mr. H. E. Burke, Specialist in Forest Entomology ; Prof. R. W. Doane and Mr. 

 G. F. Ferris, of the Stanford University Department of Entomology ; and Mr. George P. 

 Gray, of the University of California Insecticide Laboratory, all of whom offered helpful 

 suggestions during this study. Mr. R. D. Hartman assisted in the control experiments. 

 150829°— Bull. 838—20 1 



