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ARREST RAVAGES 



^ OF ROSE MIDGE 



This is the month when the rose midge conducts its fall campaign, which 

 this year appears to he widespread and fraught with danger for this crop. 

 Precautions are simple, and preventive measures are known. Explana- 

 tion of them in this article enables growers to combat this pest effectively. 



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ANGEEOUS as ever, the 

 midge is again engaged in 

 its depredations in many 

 rose-growing establish- 

 ments this fall. This is a 

 time of year when it is 

 usually active, but this 

 season its effects seem to 

 be noted more widely than 

 ordinarily is the case. In- 

 quiries have reached the office of The 

 Eeview daily, sometimes several a day, 

 from rose gfrowers who found numbers 

 of blasted buds on their rose plants. 

 In some cases the growers were sus- 

 picious of the ci'use cf the trouble; in 

 others they were ignorant of the male- 

 factor. All wanted to know the most 

 «ffective way to combat this pest. 



Experiments have 

 found that while gener- 

 ations of the midge 

 mature every two 

 weeks during the sum- 

 fner months, the periods 

 when they seem to be 

 most active are from 

 the latter part of May 

 to early July and trom 

 « a r 1 y September to 

 November 1. After the 

 last date the larvae 

 enter the ground and 

 construct cocoons for 

 over winter. Just now, 

 therefore, is the time 

 when the midge is most 

 destructive and when 

 combative measures 

 will be most valuable. 



Deacription. 



The worm, or larva, 

 which does the dau;age, 

 is 80 small as to be 

 scarcely visible to the 

 naked eye. The adult 

 insect, or fly, is only 

 about one-twentieth of 

 an inch long. The egg, 

 which is shown, greatly enlarged in 

 size, in the upper right-hand corner of 

 the illustration on this page, is about 

 one-seventy-fifth of an inch long. In 

 the upper left-hand corner is the newly 

 hatched larva; belo^ is the fully grown 

 larva. To the right, below, is the im- 

 mature pupa in the cocoon. The length 

 of the full-grown larva is about one- 

 twelfth inch. The eggs, the larvae and 

 the bodies of the flies are all of a 

 yellowish color. 



The larvsB do the actual damage. As 

 soon as they are hatched they cut into 

 the pith or heart of the bloom or leaf 

 bad, completely blasting it. Though 



the general growth of the plant is not 

 impeded, the flower buds, which the 

 midge prefers, or, in their absence, the 

 leaf buds, droop to one side, turn black 

 and in time fall off. 



Uf e Oyde. 



The female midge, with her long 

 ovipositor, places the 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. The larvae grow rapidly, reach- 

 ing maturity in from five to seven days, 



Larvae of the Rose Midge (greatly enlarged) and Their Work. 



and, when full grown, work their way 

 out of the buds and fall on and enter 

 the ground, where they construct small 

 silken cocoons, 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 for experimental ob- 

 servation, the life of an adult is from 

 one to two days. The total cycle, there- 

 fore, under greenhouse conditions, is 

 from twelve to sixteen days. 



Although larvae have been observed 

 injuring buds as early as February 22, 

 under normal conditions they do not 

 appear in injurious numbers until June 



(tr July. In Department of Agriculture 

 experiments at Washington adults were 

 reared in early May from larvae which 

 pupated in November. During the 

 warm summer months the generations 

 may mature every two weeks and over- 

 lapping of broods probably takes place. 

 Larvae have been observed to be es- 

 pecially injurious during two periods of 

 the year, namely, from the latter part 

 of May to early July and from early 

 September to November 1. On the ap- 

 proach of eold weather the stages are 

 slightly prolonged and about the latter 

 part of November the larvae enter the 

 ground and construct cocoons. No in- 

 jury has been reported during winter. 

 Boses, especially the hybrid teas, are 

 apparently the only plants attacked by 

 this insect. This fact 

 has led to one sugges- 

 tion to rid houses of 

 the midge, the so-called 

 rotation method. Ac- 

 cording to this plan, 

 one must throw out the 

 rose plants entirely, 

 clear the benches of all 

 soil, whitewash them 

 and plant to carnations 

 or some crop other than 

 roses for the period of 

 a year. At the end of 

 that time, supposedly, 

 roses may again be 

 grown without danger. 



ControL 



The opinion of De- 

 partment o f Agricul- 

 ture observers is "that 

 a severe infestation of 

 the rose midge can be 

 controlled, if not en- 

 tirely eliminated, in a 

 comparatively brief 

 period by the careful 

 application of tobacco 

 dust on the soil and by 

 persistent nightly fu- 

 migation^ with tobacco in the form of 

 stems, nicotine papers, or one of the 

 volatile nicotine extracts. Where earth 

 walks are present it is advisable t« 

 spray the walks with a five or ten per 

 cent kerosene emulsion. ' ' This is borne 

 out by the methods of control used by 

 rose growers after practical experimen- 

 tation. 



After conducting experiments in con- 

 trol of the midge, experts of the De- 

 partment of Agriculture cleaned the 

 pest out of a Maryland range in the 

 following manner: All of the rose beds 

 in the infested houses were covered, 

 October 12, with tobacco dust averag- 



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