14 SECOND REPORT ON ECONOMIC BIOLOGY. 



of mangels or beet. Numerous suggestions have been put forward 

 as to the control of this insect, but in spite of these it has continued 

 to increase and devastate annually a larger acreage. 



Acting upon the suggestion of certain growers, I have made a 

 thorough and detailed study of the insect in its various stages, and 

 have carried out a number of experiments, the whole of which are 

 here set forth. 



II. ECONOMIC IMPORTANCE. 



This insect seems to have first been noticed in this country in 

 1846. In Cumberland in 1876 mangels suffered heavily, and this 

 continued in the following years to such an extent that in a great 

 measure they dropped out of cultivation (See Ormerod 1 ). Miss 

 Ormerod 1 refers to attacks in Westmoreland and Cumberland in 1880. 



Curtis 2 described the fly in 1847 from male examples under the 

 name of AntJiomyia betac, and stated " These insects will seldom 

 cause any loss to the mangel-wurzel crops, should they ever abound 

 to any extent ; but whether they would prove injurious to cattle when 

 the leaves are given as food, I am not prepared to say, but I should 

 think not, as the skins are very tender." (p. 397). 



Carpenter 3 mentions that in addition to the direct injury to the 

 plants by the leaves, they possibly render them liable to attack by the 

 Rot-fungus (Phoma betae). 



There are numerous references mentioning the occurrence of the 

 fly on either beet or mangels in the popular agricultural and gardening 

 papers during the past fifteen years, and of allied species, in other 

 countries. 



III. DISTRIBUTION. 



So far as I can learn this species is generally distributed over the 

 British Isles. Carpenter makes frequent mention of it in Ireland in 

 his Annual Reports, and I have received it from all parts of England, 

 Scotland, and Wales. 



1 A Manual of Inj. Insects, London, 1890. 2nd ed. 



Tourn. Roy. Agric. Soc., 1847, vol. viii, pp. 399-416, 1 pit. 

 3 EC. Proc. R. Dublin Soc., 1905, vol. i, pp. 289-291, pits, xxiii, xxiv. 



