MANGOLD OR BEET FLY. 145 



The Beet Fly damages the crops by means of its maggots, 

 which feed on the pulp of the Beet or Mangold leaves, and 

 thus reduce the leaves, or large patches of them, to nothing 

 but dry skin. This kind of attack does not appear to have 

 been generally observed in the country till the year 1880, 

 when the "Mangold maggot " was prevalent in many localities, 

 and especially in Westmoreland and Cumberland, where, of 

 1624 acres of Mangolds grown in those counties, it is reported 

 that all were infested. It had, however, been noticed in 

 Cumberland several years before the above date ; on which 

 subject Mr. Watson Hornsby, of Abbey Town, Holme Cultram, 

 Cumberland, favoured me with the following note : — "It would 

 appear, however, that the insect has proved itself a pest to 

 Mangold-growers in Cumberland several years previous to the 

 one you name" (1880, Ed.). In 1876 the Mangolds on the 

 farm I then occupied were much injured by it, but this was 

 the first year that I had noticed the maggots in the leaves, 

 although for some years previous to that the leaves of the 

 young Mangold plants had presented, at certain stages of 

 their growth, that shrivelled-up appearance which is a sure 

 sign of the attack of the maggot ; and I have no doubt that it 

 was so, though at the time the injury was ascribed to other 

 causes, frosts, &c. The attacks, however, were not very severe 

 or general vntil 1876, since which the Mangolds have suffered 

 heavily every summer, so much so, indeed, that in many dis- 

 tricts they have been dropped out of cultivation in a great 

 measure, only a few patches being grown in situations 

 peculiarly adapted to their growth (August 26th, 1885). 



The eggs of the Mangold Fly are very small, snow-white, 

 and oval (see fig., p. 144, much magnified, by Farsky, showing 

 honeycomb-like markings). These are laid in small patches 

 beneath the leaves ; as soon as the maggots are hatched they 

 bore through the skin of the leaf, and, being voracious, clear 

 away the substance rapidly. The maggots are about the 

 third of an inch long, legless, cylindrical, blunt at the tail, 

 and tapering to the head, which carries two black hooks by 

 means of which it cuts away the pulp of the leaf. The colour 

 is yellowish white, but sometimes green, especially towards 

 the tail, from the intestines filled with green food showing 

 through the thin skin. They feed for about a month, and 

 then turn to chestnut-brown pupse, sometimes in the leaves, 

 but commonly they quit the leaves and pupate in the ground 

 about three inches below the surface and near the attacked 

 plant. 



In summer the flies come out in about ten days or a fort- 

 night. These are ashy grey, with various darker markings, 

 and with black bristly hairs ; and about half an inch across 



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