UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 250 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



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Washington, D. C. 



PROFESSIONAL PAPER 



Jnly 24, 1915. 



FOOD PLANTS OF THE GIPSY MOTH IN AMERICA. 



By F. H. Mosher, 

 Entomological Assistant, Gipsy Moth and Brown-Tail Moth Investigations. 



CONTENTS. 



Page. 



Scope of the investigation 1 



Equipment of the laboratory 4 



Methods of conducting laboratory ex- 

 periments 4 



Difficulties in conducting the experi- 

 ments 5 



Food plants tested 5 



Combination-tray experiments 27 



Page. 



Classification of food plants 33 



The forest problem 35 



Recommendations for orchard prac- 

 tice 35 



The city problem 36 



Index of food plants used in experi- 

 ments 36 



SCOPE OF THE INVESTIGATION. 



Since the time the gipsy moth (Porthetria dispar L.) became 

 abundant enough in Massachusetts to require treatment in order to 

 prevent the defoliation of trees and shrubs the question of its favored 

 food plants has been under consideration. 



During the period from 1890 to 1900 an attempt was made by the 

 State of Massachusetts to exterminate this insect, and a study of the 

 different species of plants upon which the caterpillars would feed was 

 made prior to 1896 and published that year by Forbush and Fernald 

 in their report on the gipsy moth. These experiments were carried 

 on with nearly full-grown caterpillars, a small number being confined 

 in a jar with each food plant. If no feeding was noted in three days 

 the experiment was repeated with other caterpillars, and if the same 

 result was secured for this lot the food plant was considered unfa- 

 vored by the caterpillars. As a result of these experiments 477 

 species of trees, shrubs, and plants were tested, and 458 of these were 



Note. — This bulletin reports a series of investigations conducted in 1912, 1913, and 

 1914 to determine the favored food plants of the gipsy moth. The subject is of interest 

 to entomologists and to State authorities engaged in the fight against the gipsy moth in 

 the northeastern States. 



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