18 



The Florists^ Review 



Mat 16. 1019. 



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HOW TO CONTROL ROSE MIDGp 



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TOBACCO WILL DO IT. 



Says U. S. Department of Agriculture. 



Midge, one of the moat destructive 

 pests the rose growers of America ever 

 have had to contend with, and one which 

 becomes more widely distributed and 

 devastating each season^ may be con- 

 trolled by such simple means as the use 

 of tobacco dust and stems, according 

 to the United States Department of 

 Agriculture, which has just published 

 the results of a series of experiments 

 conducted by E. E. Sasscer and A. D. 

 Borden in an infested establishment at 

 Colgate, Md., near Washington. 



"It is evident,^' says the report, 

 "that ,a severe infestation of the rose 

 midge can be controlled, if not entirely 

 eliminated, in a comparatively brief 

 period by the careful application of to- 

 bacco dust on the soil and by persistent 

 nightly fumigation with tobacco' in the 

 form of stems, nicotine papers, or one of 

 the volatile nicotine extracts. Where 

 earth walks are present it is advisable 

 to spray the walks with a five or ten 

 per cent kerosene emulsion. ' ' 



History and Distribution. 



This rose pest was first collected in New 

 Jersey in 1886. It was collected later in 

 New Jersey in 1889, in New York in 

 1890, in the District of Columbia in 1891, 

 1894 and 1896, in Massachusetts in 1894, 

 and in Chicago in 1897. In 1903 speci- 

 mens were sent to the Bureau of En- 

 tomology from Cleveland, infesting the 

 Meteor variety, with the report that as 

 many" as thir*ty-five larvae had been taken 

 from a single' bud. Apparently the same 

 insect wsis received from Cincinnati in 

 1905, where it was seriously damaging 

 the buds and. tips of the La France and 

 Duchess of Albany. Notwithstanding 

 the fact that in the houses containing 

 both varieties the heat was turned off 

 throughout the entire winter, the corre- 

 spondent reported that the hibernating 

 midge was not killed. 



In 1911 a heavy infestation of the 

 variety My Maryland was reported from 

 Bhode Island, and in 1915 Hewitt re- 

 corded the occurrence of this midge in 

 a garden at London, Ont., infesting 

 shoots of the variety Mrs. J. Laing. In 

 1916 Gibson reported it from the same 

 locality and also in greenhouses at To- 

 ronto. Snodgrass includes the rose 



The Rose Midge (Dasyneura rhodopbaga). 



(EDlarged about 30 diameters: A. eKirs; B. youriR larva; C, full-grown larva; D, cocoon; E. pupa; 

 F, adult male; U, adult female; H, female ovipositor). 



midge among the important insect pests 

 of Indiana, and Crosby and Leonard 

 state thaf^it attacks roses grown in the 

 open in New York. 



Although the rose midge has been re- 

 ported frequently from several states, 

 it does not necessarily follow that these 

 infestations are still in existence, since 

 some of the varieties subject to infesta- 

 tion have been given up for more re* 

 sistant and profitable varieties, and in 

 others the insects may have been ex- 

 terminated by the use of insecticides. 



Much Damage Done. 



The rose midge, Dasyneura rhodo- 

 phaga (Coq.), an insect related to the 

 Hessian fly, is often the cause of con- 

 siderable injury to roses grown under 

 glass. In 1912 Davis estimated that the 

 loss due to this pest in two Chicago 

 greenhouses would approximate ^10,000 

 annually. Subsequently this insect was 

 reported by various entomologists as be- 

 ing especially injurious to the flower 

 and leaf buds of the rose, distorting 

 their growth and eventually causing 

 them to turn brown and die. 



In the fall of 1916 an infestation was 

 located at Colgate, Md., which, accord- 

 ing to the owner, caused an annual loss 

 of from $4,000 to $6,000. Although the 

 house was generally infested, the in- 

 festation was limited to the following 

 varieties of roses: Badiance, Hadley, 

 Bussell and Killarney. Hadley and 

 Badiance varieties were most severely 

 infested, scarcely a leaf or flower bud 

 • scaping attack. 



This infestation offered an excellent 

 opportunity for determining a satisfac- 

 tory means of controlling this pest in a 

 commercial greenhouse, and, in collabo- 

 ration with Prof. E. N. Cory, entomolo- 

 gist of the Maryland Agricultural Ex- 

 periment Station, the investigation was 

 begun in October, 1916. 



Life History. 



It was found that the female midge, 

 with her long ovipositor, places small 

 yellowish eggs just under the sepals of 

 the flower buds or between the folded 

 leaves of the leaf buds. Under favor- 

 able temperature conditions these eggs 

 hatch in two days, and the young larvae, 

 or maggots, immediately attack the 

 buds, extracting the sap and eventually 

 causing the petals and leaves to dry up 

 and die. They grow rapidly, reaching 

 maturity in from five to seven days and, 

 when full grown, work their way out 

 of the buds and fall on and enter the 

 ground, where they construct small 

 silken cocoons (fig. 1, D) in which they 

 pupate. Adults appear in from five to 

 seven days, and shortly after deposit 

 eggs for the next generation of larvae 

 or maggots. In confinement, the life of 

 an adult is from one to two days. The 

 total cycle, therefore, under greenhouse 

 conditions, is from twelve to sixteen 

 days. About eighty-five per cent of the 

 adults reared in cages were females. 



Seasonal History. 



Although larvae or maggots have been 

 observed injuring buds as early as 

 February 22, under normal conditions 

 they do not appear in injurious numbers 

 until June or July. In Washington 



