U. S. D. A., B. E. Bui. 04, Part VI. Issuetl August 1, 1909. 



SOME MISCELLANEOUS RESULTS OF THE WORK 

 OF THE BUREAU OF ENTOMOLOGY-IX. 



THE GREEimOUSE THRIPS. 



(Hcliothrips hxmorrhoidalis JJouche.) 

 By H. M. Russell, 

 Agent and Ex-pert. 



INTRODUCTION. 



This insect has been known since 1883 to have been the cause of 

 much injury to greenhouse plants; but its life history has never been 

 fully worked out.*^ The writer, while engaged in field work in the 

 State of Florida during 1907, had his attention called to a "diseased" 

 condition of crotons in one of the greenhouses at Orlando. This 

 condition was found to be caused by the extreme abundance of a spe- 

 cies of thrips feeding on the foliage. Specimens of the adult were 

 sent to Dr. W. E. Hinds, who determined them to be IleliotTirips 

 Jixmorrhoidalis Bouche. Wliile working under the direction of 

 Dr. F. 11. Chittenden during the winter of 1907-8, the writer made a 

 study of this insect's life history and the means by which it might be 

 controlled. 



HISTORY. 



The species was first described by Bouche,^ in 1833, as TJirips 

 Tisemorrhoidalis from specimens taken in a greenhouse in P^urope. At 

 that time he wrote that he believed the native land of the species to 

 be America. That this supposition was correct appears evident at 

 the present time. 



Packard/" writing in 1870, described this species for the first time 

 from this country. He wrote: "This is one of the greatest pests in 

 our hothouses. It is the Ileliothnps Tisemorrhoidalis of Burmeister." 

 Packard called it the greenhouse thrips and gave a meager descrip- 

 tion of the larva and adult, and an illustration of the latter, but 

 neither descriptions nor drawing are exact enough to identify speci- 

 mens. He furnished a list of food plants, a description of injury, 

 and recommended washing plants with soapsuds as a remedy. 



«The external and internal anatomy of this insect has been fully worked out by 

 several European entomologists, while others have made incomplete studies of the 

 life history on the Continent. 



43 



