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PREFACE. 



Within the past three years insect injury to violets grown under 

 glass has been very pronounced and has been the occasion of consider- 

 able correspondence and investigation in this Division and of experi- 

 ment in the line of remedial treatment, conducted chiefly by the 

 Division of Vegetable Physiology and Pathology of this Department. 

 Messrs. A. F. Woods and P. H. Dorsett, of that Division, were in 

 charge of this work, and the latter gentleman, who is also a practical 

 florist, has furnished much material for the investigations conducted at 

 this office. The insects which have been the occasion of the principal 

 injury and which have received the larger share of attention in the 

 present bulletin are five in number: (1) The caterpillar of a small moth, 

 which we have called the greenhouse leaf-tyer ; (2) the larva of a hymen- 

 opteron, which will be called the violet sawfly; (3) a plant-louse unde- 

 scribed at the time work was begun on this class of insects and known 

 to violet growers as the black or brown aphis or "black fly;" (4) the 

 common "red spider," and (5) a small maggot called by florists the 

 "gall fly." Several instances of injury by the larva of the moth above 

 mentioned, to violets and other greenhouse plants, have been published; 

 and the red spider is altogether too well known as a pest everywhere. 

 None of these species has been at all f u\lj treated biologically and 

 economically in any of the publications in which they have hitherto 

 been considered, and none has been figured in Departmental publica- 

 tions with the exception of the gall fly, which was described specifically 

 in an earlier bulletin of this series. Numerous other insects have been 

 observed upon violets in recent years, and some have been sent in by 

 correspondents, particulars concerning which will be given. Certain 

 common greenhouse pests other than those which will receive special 

 mention, such as white grubs, wireworms, and sow-bugs, are occa- 

 sionally troublesome to violets. Several species of cutworms have 

 been observed from time to time attacking violets, and these will be 

 considered with such other insects as have been recorded in our Divi- 

 sional notes and in literature as occurring on this genus of plants. 



Several other species of greenhouse pests, notably such as infest the 

 buds and blossoms of roses, have been conspicuous in recent years, 

 and certain of the more interesting of these will be duly considered in 

 accordance with their injuriousness. Prominent among these are 



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