THE CABBAGE-FLY : ITS INJURIES TO ITS FOOD-PLANTS. 185 



destruction of cabbage crops. It commeuces its attack upon the young 

 plants while yet in the seed-bed, and continues to infest them, in 

 several successive broods, until they are taken up in the autumn. The 

 larvae operate by consuming the rootlets of yoimg plants, and by ex- 

 coriating the surface and eating into the rind of older ones, or even 

 penetrating into the interior of the root. When they abound to the 

 extent of seriously burrowing the stalk, the decay of the root frequently 

 follows, in wet seasons, and entire fields are thus destroyed. They are 

 usually to be found in the swellings upon the roots, and the species is 

 one of those which Curtis notices as infesting " anbury." 



Its Injuries not Confined to Cabbages. 



It also attacks the turnip, mining into its interior in an irregular 

 burrow, or occupying eroded spots upon its outer surface. " Sometimes 

 a small roughened spot is seen, appearing like a crack in the skin of 

 the turnip, with its edges rough and ragged and turned outward, and 

 on paring off the roughened spot a plump white maggot is come upon, 

 lying in a cavity it has there made for itself. At other times a larger 

 eroded spot occurs, which is filled with wet and slimy dirt. On re- 

 moving this dirt, the surface is found to be rough and warty, with 

 little grooves here and there, in each of which is a maggot." (Fitch). 



Kirby and Speuce {Introduc. Entomol., 1846, jd. 140) evidently re- 

 fer to this species, when they mention that "one of the most delicate 

 and admired of all table vegetables, concerning which gardeners are 

 most apt to pride themselves, and bestow much pains to produce to 

 perfection — the cauliflower — is often attacked by a fly, which, ovi- 

 positing in that part of the stalk covered by the earth, the maggots, 

 when hatched, occasion the plants to wither and die, or to produce a 

 worthless head." 



When and Where First Described. 



A. hrassicm was described by Bouch^ in 1834, as above cited. It is 

 thought by Schiner,* that it may have been previously described by 

 Meigen, in 1826, as A. rxijicep^. If the two are hereafter shown to be 

 identical, then the northern range of the cabbage-fly will be extended 

 into Greenland, whence examples of A. rtificeps have been received. 

 There is an older A. brassicm, viz. that of Weidemann {Zo'dlog. Mag., i, 

 p. 87), which is a different species, and has recently been referred by 

 Mr. Meade to A. raclicum Linn.f 



* Schiner, Fauna Austriaea, Dipt., i, p. 644. 



tWith A. rvficeps Meigen, Mr. Meade is not acquainted. 



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