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TWO DIPTEROUS INSECTS INJURIOUS TO CULTIVATED FLOWERS. 



By D. W. COQUILLETT. 



A DESTRUCTIVE LEAF-MINER ON THE CHRYSANTHEMUM. 



Next to the rose, there are few flowers more widely cultivated and 

 admired in this country than the chrysanthemum. So great, indeed, 

 is its popularity that annual fairs are held in various localities devoted en- 

 tirely to an exhibition of specimens of this queenly flower. Within quite 

 recent years a pest has made its 

 appearance which, if not destroyed 

 early in its career, will severely 

 disfigure if it does not succeed in 

 killing the plants outright. I^ot 

 only are the various kinds of 

 chrysanthemums thus attacked, 

 but cinerarias, eupatoriums, and 

 tansy are also subject to its depre- 

 dations. One grower, in trans- 

 mitting specimens of the infested 

 leaves to the Department, writes 

 that he will be compelled to aban- 

 don the growing of these plants 

 owing to the attacks of this pest. 



The latter when in the adult 

 state is a small, black, two-winged 

 fly, representeH.1 in the accom j)any- 

 ing engraving (Fig. 45). The front 

 of the head, the face, halteres, 

 knees, and posterior margin of 

 each segment of the abdomen are 

 yellowish. The larva, which is 

 of a pale yellowish color, with the 

 mouth-parts black, forms long, discolored mines in the leaves, usually 

 in the blade of the leaf, but sometimes in the petiole, and i^asses the 

 pupa state within the mine. The species was described a few years 

 ago under the name of Phytomyza chrysanthemi — by Mr. Kowarz. 



The first specimens of this pest were received at this Department 

 December 30, ISSG, from Charles Anderson, of New York; these were 

 still in their mines in the chrysanthemum leaves, with the exception of 

 two of the adults, which had issued on the way. Others put in tbeir 

 appearance at intervals up to January 10, and on the 6th of the latter 

 month two were observed to be still in the larva state. 



A package of leaves of the Marguerite, or French daisy {Chrysan- 

 themum frut€scens)j infested by this pest was received January 14, 

 1887, from the well-known horticulturist. Prof. Thomas Meehan, of 

 Germantown, Pa. 



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Fig. 45. — Phytomyza chrysanthemi: adult fly, 

 above— enlarged ; auteuna of -same, to left — more 

 enlarged ; leaf showing larval mines, below — natu- 

 ral size ; larva, at left, pupa at right — both enlarged 

 (original). 



