UNITED STATES DEPARTMENT OF AGRICULTURE 



% BULLETIN No. 833 



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Contribution from the Bureau of Entomology. 

 L. O. HOWARD, Chief. 



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Washington, D. C. 



May 31, 1920 



CHRYSANTHEMUM MIDGE. 1 



By C. A. Weigel and H. L. Sanford, Collaborator's, Tropical and Subtropical Fruit 



Insect Investigations. 



CONTENTS 



Page. 



General description 1 



Historical 2 



Distribution in the United States and Canada. . 3 



Varieties affected 4 



Economic importance - 4 



Technical description 6 



Page. 



Life history and habits 7 



Natural enemies 13 



Experiments in control 14 



Summary of control and recommendations 21 



Preventive measures 22 



Literature cited 23 



GENERAL DESCRIPTION. 



The chrysanthemum midge, Diarihronomyia Jiypogaea (F. Low), 

 is a European insect which gained entrance into the United States 

 a few years ago and since then has been reported as injurious from 

 widely separated localities in this country and Canada. 



When chrysanthemums are infested by this midge, the attention 

 of the casual observer is most likely to be drawn to the presence of 

 galls. These galls occur on the leaf, stem, or flower head of the 

 chrysanthemum plant. (See PI. I, B and C.) After the larvse hatch 

 from the orange-colored eggs, which are deposited by the adult 

 female on the surface of tender tips and new growth, they bore their 

 way into the tissues, thereby giving rise to the galls. 



The galls are cone-shaped and generally project obliquely from the 

 surface. The length of the gall when fully developed is about one- 



1 The account of the chrysanthemum midge contained in this bulletin is the result of an investigation 

 which was undertaken with the intention of providing further data on the life history and habits of this 

 insect, as well as more satisfactory means of control. The preliminary life-history studies which were 

 started in February, 1917, by A. D. Borden, of the Bureau of Entomology, were subsequently taken up 

 by H. F. Dietz, of the Federal Horticultural Board. Further studies on life history and control were 

 inaugurated and carried to completion by the writers as a result of the many inquiries for advice as 

 well as the outbreaks reported during the chrysanthemum season of 1918 and the spring of 1919. During 

 the entire period the work has been under the constant supervision of E . E . Sasscer, chief inspector of the 

 Federal Horticultural Board and collaborator of the Bureau of Entomology. 



150054°— 20— Bull. 833 1 



