AprH, '15] 



ENTOMOLOGISTS' PROCEEDINGS 



267 



Mr. McConnell has shown the actual financial value of these nodules 

 to the farmer as compared with the cost. of sodium nitrates. 



President H. T. Fernald : In the case of the papers remaining 

 on the program, the authors are either absent or wish the papers 

 presented by title. 



At the close of this session, the regular business was transacted and 

 the meeting adjourned at 11.30 a. m. 



A New Pest, The Chrysanthemum Midge {Rhopalomyia hypogaea H. Lw.) 



Specimens of badly infested chrysanthemum plants were received under date of 

 March 27, 1915, from Prof. R. H. Pettit of the Michigan Agricultural College, ac- 

 companied by the statement that the above named insect, determined by the writer, 

 was causing serious injury in the houses of a commercial chrysanthemum grower. 

 Certain varieties^ particularly mistletoe, appear to be very susceptible to injury. 

 The plant submitted for examination had the stem from a point at about the surface 

 of the ground to the region of the leaves, a distance of 1.5 cm., enlarged to practically 

 twice the normal diameter, the swelling being composed of nearly approximate oval 

 cells, each of these having a length of about 2 mm. Similar masses of infested tissue 

 occurred in and near the midribs of the developing leaves and arrested the growth of 

 the fohage, producing a close, ill-shaped head and the probable ruin of the plant for 

 commercial purposes. A study of the, midges and the deformities they produce con- 

 vince us that this is an European species recorded from central and southern Europe 

 as infesting Chrysanthemum leucanthemum, C. corymhosum, C. atratum and C. japoni- 

 cum, and producing galls on the stalks, leaves, buds and presumably also on subter- 

 ranean root stalks. The individual galls frequently form sub-conical projections from 

 the swollen surface of the plant tissues. 



This insect, hke allied greenhouse species, probably breeds continuously when 

 conditions are favorable, the initial attack being usually confined to buds (including 

 the subterranean ones on root stalks) or tissues just unfolding from the buds. The 

 midges transform in. the gall and it is probable that hibernation or aestivation occurs 

 either in the adult or possibly as larvae in slowly developing, subterranean buds. 

 The probabilities favor this insect being a serious local pest, since it has presumably 

 become estabHshed in this country without its full complement of parasites. It is 

 certainly desirable to ascertain the present distribution of the chrysanthemum midge 

 in America, and growers of this popular flower would do well to adopt every reasonable 

 precaution to keep their stock free from this insect. Badly infested plants should 

 be burnt, and it is possible that, by cutting off and destroying infested portions of 

 others, it may be practical to exterminate the insect in locahties where it has become 

 estabHshed without resort to more drastic measures. Fumigation with hydrocyanic 

 acid gas, while deadly to the midges on the wing, would have httle or no effect on the 

 larvae and could not be expected to accomplish more than prevent the insect from 

 becoming excessively abundant. 



E. P. Felt. 



