DIPTEKA OR TEUE FLIES. 



219 



ing the yoiing plant : they lie lengthways up the plant, and 

 reach one-fourth of an inch in length.^ The puparia are found in 

 May, from whicli the fly comes out in July. The imago is very 

 like the Onion Fly : the thorax is 

 grey) with pale sides and with 

 stripes ahove ; ahdomen ashy -grey 

 with an indistinct dorsal stripe ; 

 legs black with pale tibise ; abdomen 

 hairy. The female is entirely ashy- 

 grey, posterior and middle femora 

 and tibicB pale. The attack often 

 foUows on fallow land, and it has 

 been noticed to occur after the land has been dressed with pond 

 mud. Probably couch-grass harbours this iiy. Where it is prev- 

 alent, as in some Fen districts, the seed should be sown thickly. 



The Mangold Wubzel Fly (Chortophila (Pegomyia) bet^). 



Amongst the pests common to Mangolds and Beets the Wurzel 

 Fly is perhaps the most important. This insect is an ashy- 



Vic. 110. — Wheat-bulb Fly 

 b, hnvyii ; c, pupariuiit 



Fio. 111. — ^Tanoold Fly (CJtnrtophila &eto). 



1 and 2, Male, nat. .size, and mag. ; .i and 4, feBiale, nat. size, and mag. ; G and fi, 

 larva, nat. size, and mag. , 7 and 8, puparium, nat. size, and ma^. (Whitehead.) 



grey fly with black bristles, very similar to the Onion Fly in 

 general appearance. The)' occur as early as l\Tay, when they 



Some now and then reach one-third of an inch in length. 



