1921 ENTOMOLOGICAL SOCIETY. 63 



NOTES ON THE CONTROL OF THE ROSE MIDGE. 



William A. Ross, 

 Dominion Entomological Laboratory, Vineland Station. 



At the annual meeting of this Society held at Guelph in 1916, Mr. Arthur 

 Gibson, of the Dominion Entomological Branch, directed your attention to a serious 

 greenhouse pest — the rose midge — which recently had been introduced from United 

 States into Canada.* At that time, it was present only in one greenhouse, but 

 since then it has been found in seven other greenhouses. 



The experience of florists, both in United States and Canada, has shown that 

 this insect when present is by far the most destructive pest of roses. In 1919 

 its depredations in one Ontario greenhouse caused a loss of twelve thousand dollars, 

 and in another six to seven thousand dollars. 



The following description of the injurious habits and life history of the rose 

 midge is taken from a short article, which the writer published in the Agricultural 

 Gazette of Canada, Vol. 6, No. 2, Eeb. 1919. 



Nature of Injury. " When very abundant, the larvae of the midge — whitish 

 maggots — may be found feeding on any succulent part of the rose bush, as for 

 instance, at the base of the flower buds, within the buds, on the upper side of 

 tender leaves, and on leaf petioles. However, the usual point of attack is on the 

 young shoot in the axil of a leaf petiole. Infested shoots grow crooked, and, as 

 a general rule, wither and die. Affected flower buds, when not killed outright, may 

 be so disfigured as to be unsaleable." 



Life History. " The adult insect is a fragile two-winged fly, less than 1/16" 

 in length. The female deposits her eggs between the folded leaves of the leaf buds, 

 and to some extent in the axils of tender leaves and between the sepals and petals 

 of the blossom buds. Under greenhouse conditions the eggs hatch in about two 

 days. The maggots, as previously stated, feed on the tender tissues of shoots and 

 buds, and become mature in from .five to seven days. They then drop to the soil, 

 change to the pupal stage and emerge as adult flies in about six days." 



"The midge is most abundant and destructive during summer. With the coming 

 of autumn it declines in numbers and by winter wholly disappears from the rose 

 plants. It remains dormant in the soil through the winter months, and does not 

 reappear again until the last of February or early March." 



Control. Various methods of combating this pest have been tested or at 

 least recommended — and among others the following: 



Crop Rotation and Thorough Cleaning of House in Mid Winter. At 

 the time the attention of the Entomological Branch was first directed to this pest 

 only two reliable methods of controlling it were known, namely: (1) the growing 

 of another crop instead of roses for one year, and (2) the destruction of all the 

 plants and the removal of the soil in mid winter. Both of these methods would 

 entail a very serious derangement and loss in business, and for tin's reason the 

 growers refused to consider them until all other possible remedies had been 

 exhausted. 



* The Superintendent of the 1 Dale Estate, Bramipton, informs me that a pest, which 

 he believes was the rose midge, was present in one of the Dale rose beds fifteen years 

 agio. It was very destructive that year, but wholly disappeared after the soil in the 

 infested bed was thrown out in March. 



