50 MASS. EXPERIMENT STATION BULLETIN 157. 



the flies. Especially serviceable seems to be SaUicus senicus Clerk (identi- 

 fied by Mr. J. H. Emerton of Boston), a gray, brownish, and white form, 

 about one-fourth of an inch long, common in and outside of houses all over 

 North America. The front of its head around and above the eyes is 

 white; there is a white band across the anterior end of the abdomen, and 

 two or three obhque wliite bands on the sides. In some cases a longitudi- 

 nal white band passes down the middle of the abdomen. This spider is a 

 plant crawler, and the writer has observed individuals again and again 

 on the marguerite plants, prejdng upon the adult flies. 



According to Mr. Whiting of the Department of Floriculture this spider 

 is very valuable in greenhouses in general, preying extensively on the 

 various aphids, on the Rose Leaf-roller (Archips rosaceana Harris), ex- 

 tracting the larva from out of the rolled leaf, and on other injurious forms. 



Insect Parasites. 

 As far as the writer knows, no definite insect parasite of the Margueiite 

 Fly has as yet been reported. The late Mr. D. W. Coquillett, however, was 

 of the opinion that such a parasite exists. Referring (Insect Life, VII., 

 1894-95, p. 400) to some marguerite leaves which he received from the 

 greenhouses of Mr. James Read of Irvington, N. Y., Feb. 28, 1890, from 

 which adults of the Marguerite Miner were reared, he adds : — 



Quite a large series of chalcidid flies belonging to the genus Chrysocharis were 

 also bred, but as the other members of this genus are almost without e.xception 

 parasitic upon other chalcidid or Ichneumon flies, it is quite certain that the 

 present specimens did not prey upon the leaf miners. Their presence, however, 

 is indicative of the very important fact that these miners have an enemy to contend 

 with in the form of a small four-winged fly that has thus far escaped detection. 



SUMMARY OF RESULTS. 

 History and Distribution. 



The Marguerite Fly, or Clirysanthemum Leaf Miner is, as far as Icnown, 

 a native insect. It was first reported from a greenhouse near Glen Cove, 

 N. Y., in the fall of 1886. It has since been found in many other localities. 

 At the present time it is definitel}'' known to occur in the foUouang States: 

 New Hampshire, Massachusetts, Connecticut, New York, Pennsylvania, 

 Illinois, Wisconsin and Montana. It is doubtless present in other States. 



Host Plants. 

 The food plants of tliis insect are apparently restricted to the family 

 Compositse. Of the cultivated plants, marguerites and feverfews seem to 

 be the favorites. It is also known to attack eupatoriums, gazanias, 

 helianthus, cinerarias, tansies, chrysanthemums, goldenrod, ragweed, 

 dandelions, beggar-ticks, wild carrot, the common white or ox-eye daisy, 

 and everlasting, or ladies' tobacco. It is essentially a greenhouse pest. 



