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2 : 
Czrcular No. 920 
September 1953 ¢ Washington, D. C. 
UNITED STATES DEPARTMENT OF AGRICULTURE 
Whe Hall Scale Eradication Project: 
By E. H. Fosen, (agent) agriculturist, Region iV, and A. W.CressMAn, entomologist, Division of 
Fruit Insect Investigations, Bureau of Entomology and Plant Quarantine, Agricultural Research Admin- 
istration, and H. M. Armirace, chief, Bureau of Entomology, California Department of Agriculture. 
CONTENTS 
Page Page 
HM GROMUCEIO Ma tts si eo eapel cies toe iE radicatiom propramiws i. ea aes 5) 
DISEHIDUCION kr ee ce ters Ds a Sutvcy andinspectiOns....cv8 5 
Hostiplants;and injury: 02). Sle abreatment 2) aorta ee ee 9 
Description of stages and habits....... Ay SUMMING sh acon Seas owe te ae aca 15 
SeasonalelistOnye sc. eon Oe Aipiciterature cited aaa ets 16 
INTRODUCTION 
The Hall scale CNelotaspis halli (Green)) was discovered in the United 
States in cue U.S, Plane Introduction Garden at Chico, Calif., by, C. F. 
Kinman in 1934. It was first found on Prunus bokhariansis and subsequently 
on many additional species and varieties of Prunus and Amygdalus. Upon 
discovery of the scale, host plants that had been shipped from the Plant 
Garden that season were located and destroyed. Inspection of many of the 
host plants shipped to various points in California from 1928 through 1933 
gave negative results, and it was decided to attempt eradication of the 
infestation in the Plant Garden (Mackie 11).2 Many trees were pulled 
and burned. Treatment of the remainder included cutting back to scaffold 
branches, scraping the bark, painting with oil emulsion, fumigating with 
hydrocyanic acid gas, and applying a special tree paint (fig.1). Fumigation 
was at the rate of 2.5 ounces of more of sodium cyanide per 100 cubic feet 
1 The work described in this circular was established as a Federal-State cooperative project 
by the U. S. Bureau of Entomology and Plant Quarantine and the California Department of 
Agriculture, under the respective supervision of D. L. Van Dine and the late D. B. Mackie. 
It was subsequently organized and directed by B. L. Boyden of the Bureau in cooperation with 
Mackie until 1945. Contributions of V. R. Jones, in charge of fumigation, H. W. Gray, in 
charge of inspection, and H. J. Crawford, in charge of biological studies, and the technical 
assistance of H.R. Yust and R. A. Fulton in developing fumigation procedure are acknowledged. 
The first four photographs were taken by Cliff Clower, of the California Department of Agri- 
culture, ‘ 
* Italic numbers in parentheses refer to literature cited, p. 16. 
249715—53— eal 
