CHRYSANTHEMUM MIDGE. 



While it is primarily a greenhouse pest, A. Gibson, in August, 

 1915, found it occurring on both greenhouse and outdoor plants at 

 Ottawa, Canada. Well-developed galls on the newly unfolded 

 leaves were found by the authors, March 26, 1919, on hardy chry- 

 santhemums which had been grown out of doors all winter at the 

 Arlington Farm, Eosslyn, Va. A careful inspection of the entire 

 stock revealed the fact that the insects had wintered over on these 

 plants in the immature stages, probably as either larvae or pupae 

 within the galls. Inasmuch as there were many empty galls present 

 on the old dead and dried leaves of the previous season's growth, 

 it was evident that this was an infestation of long standing. On 

 April 11, many adults were found entangled in webbing spun by 

 spiders among the developing new tip growth. These emerged from 

 the above mentioned galls. 



The first severe infestation of the midge brought to the attention 

 of the Bureau of Entomology was on chrysanthemums in greenhouses 

 at Philadelphia, April, 1917. The entire stock was infested, causing 

 a total loss to the grower. During the same year other florists 

 reported a total loss of their stock of chrysanthemums valued at 

 several thousand dollars. Even in the case of a light infestation 

 the foliage is practically valueless for commercial purposes, and in 

 the case of a heavy infestation the growth is completely arrested. 

 (See PI. I, C.) 



Owing to numerous reports of injury by the chrysanthemum midge 

 in the States of Indiana, Illinois, and Michigan, H. F. Dietz con- 

 ducted a survey in this territory during the months of iNTovember 

 and December, 1918, for the purpose of ascertaining the exact amount 

 of damage occasioned by this pest. From the data gathered, this 

 general locality proved to be one of the centers from which the pest 

 was being distributed over the United States. Greenhouses of 33 

 florists were visited, including some of the largest growers and dis- 

 tributors in this country. It was evident that if serious pests were 

 established in this region, it would be only a matter of a year or two 

 before such insects would be widely scattered. This is exactly what 

 has happened in the case of the chrysanthemum midge. This pest 

 was found established in 8 of 33 places visited. 



Serious injury to infested plants was noted. For example, no 

 plants of the variety Dr. Enguehard came into flower, on account 

 of their dwarfed, knotted, and knarled condition, with the result 

 that the new central stem did not form. Moreover, other varieties, 

 including Wm. Turner, were attacked just at the time the crown buds 

 were "setting/ ' causing these flowers to become distorted. As a result, 

 the flowers are not borne upright as normal flowers should be. Such 

 evidence may be taken as an indication of the presence of the midge, 

 even though the galls may not be numerous enough to attract at- 

 tention. 



