A. E. Cameron 78 



Natural control of the pest is secured by the parasitism of two species 

 of Bracouids on one or both of which a Proctotrypid is probably hyper- 

 parasitic. 



The degree of parasitism ascends to a climax at the end of August 

 and beginning of September, and then suddenly diminishes. 



Frequent hand-picking of attacked leaves and their destruction 

 provides a ready and effective means of killing the maggot and unhatched 

 eggs. This method is only practicable where the crop is a small one. 



Dressings of stimulating, chemical manures in the early stages, 

 strengthens the plants so that they maintain themselves the better 

 against the injurious effects of infestation. 



Farmyard manure which attracts the flies should where used be 

 applied in the autumn to give it the chance of decaying before the adults 

 appear in the spring. 



Deep-ploughing in the autumn serves to bury the hibernating 

 puparia which lie near the surface, thus rendering the emergence of 

 the adults in the spring a matter of comparative difficulty. 



Paraffin emulsion is not so effective in killing the maggot as this 

 same emulsion with nicotine added. 



BIBLIOGRAPHY. 



Banks, N. (1912). The Structm-e of Certain Dipterous Larvae with Particular 



Reference to those in Human Foods. U.S. Department of Agriculture, Bureau 



of Entomology, Washington, Technical Series, No. 22, p. 30, PI. VI, figs. 110, 112. 

 BoucHE, P. Fr. (1834). Naturgeschichte der Insekten besonders in Htnsicht ihi-er 



ersten Zustande als Larven und Puppen. Berlin, 21G pp., 10 pis {A.mitis Mg., 



p. 66, A. rumicis Bch6, pp. 209-210). 

 Brauer, F. (1883). Die Zweifliigler des Kaiserlichen Museums zu Wien. III. 



Systematische Studien auf Grundlage der Dipteren-Larven nebst emer Zusam- 



menstellung von Beispielen aus der Literatur iiber dieselben und Beschreibung 



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 Cameron, E. A. ( 1913). General Survey of the Insect Fauna of the Soil, etc. Journ. 



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