48 



Some of the rose growers whom I have visited inform me that they 

 exterminated these pests in their rose houses by a continued and lib- 

 eral use of Persian insect powder, and Mr. L. E. Wood writes that he 

 has complete success in tbe use of California buhach, a very similar 

 product, which has been recommended by this Division against this 

 pest for years past. One grower assures me that he accomplished the 

 same thing by a liberal use of refuse tobacco stems obtained from a 

 cigar factory. These stems were placed beneath the benches on which 

 the infested roses were growing, and some were also placed on the 

 heating pipes. The stems were quite moist when obtained, and the 

 heat of the rose house caused a constant evaporation, which was suf- 

 ficiently deadly in its effects upon these fragile insects as to result in 

 their death, without at the same time producing a perceptible injury to 

 the rose bushes. The same grower also informed me that when these 

 pests first made their appearance in one of his rose houses he had all 

 of the rose bushes in that house cut off close to the ground, only to find 

 that when these bushes began to grow the pests were soon apparently 

 as abundant as before. 



A NEW VIOLET PEST. 



(Diplosis violicola n. sp.) 

 By D. W. Coquillett. 



In Europe, two different species of Cecidomyia attack cultivated and 

 wild violets — the one, Cecidomyia violce of Franz Low, dwarfing the 

 entire plant and causing it to assume the form of a rosette through the 

 working of the larvae at the bases of the short sessile leaves ; the second 

 species, the Cecidomyia affinis of Kieffer, folds and distorts the young 

 leaves and unopened blossoms. It is somewhat curious that, although 

 sweet violets have been somewhat extensively cultivated in this country 

 for many years past, yet up to the year 1896 no complaint had been 

 made of any Cecidomyian attacking either these or any of the many 

 wild species of violets which occur in almost every locality in this 

 couutry. 



On October 5 of the above mentioned year Mr. P. H. Dorsett, of this 

 Department, brought to this office several leaves of sweet violets from 

 the vicinity of Washington, D. C, each of which was folded up in such 

 a manner as to bring the upper surfaces together; the leaves were much 

 wrinkled and distorted, and each contained from one to three Whitish, 

 or more or less yellow, legless larvae. Thirty one adults were bred 

 from these on the 23rd and 24th of the same month. Mr. Dorsett has 

 published a brief account of this pest, which is known among florists 

 as the "gall fly", together with figures of the distorted leaves. More 

 recently Dr. Howard, by request of a correspondent, has published a 

 brief accouut of this insect in a current publication. 



Plants of violets infested with what is evidently this same pest 

 were received July 17, 1896, from Mr. W. A. Hammond, of Richmond, 



