242 diptera or true klies. 



Wheat-bulb Fly (Hylemtia coarctata). 



The Wheat-bulb Fly is chiefly harmful in the Fen districts 

 to wheat, but occurs in many other parts. It is said to be 

 most destructive on land fallowed in the previous summer, and 

 where the crop has been so thin as to expose the land (Ormerod). 

 The Wheat-bulb Fly lays her eggs in the young wheat, the larva 

 living in the centre of the plant. The grub is white in colour, 

 and can be told by the curious pro- 

 cesses at the tail end. These larvae 

 are found in April destroying the 

 young plant : they lie lengthways 

 up the plant, and reach from one- 

 fourth to one-third of an inch in 

 length. The puparia are found in 

 Fm. 137.— Wheat-bulb Fly. May, from which the fly comes out 



6, Larva; c, puiKUiuni. • t i T^i • • l-l il 



m July, i he imago IS very like the 

 Onion Fly : the thorax is grey, with pale sides and with stripes 

 above ; abdomen ashy-grey with an indistinct dorsal stripe ; legs 

 black with pale tibiae ; abdomen hairy. The female is entirely 

 asliy-grey, posterior and middle femora and tibise pale. The 

 attack often follows on fallow land, and it has been noticed to 

 occur after the land has been dressed with pond mud. Probably 

 couch-grass harbours this fly. Where it is prevalent, as in 

 some Fen districts, the seed should be sown thickly, and the 

 attacked crop given a good dressing of artificial manure. 



The MANQom Fia' (Pegomyia bet.e). 



Amongst the pests common to Mangolds and Beets this 

 fly is perhaps the most important. The fly is an ashy-grey 

 with black bristles, very similar to the Onion Fly in general 

 appearance. It occurs as early as j\Iay, when it deposits 

 elongate white eggs (fig. 139, a) on the under-surface of 

 the mangold leaves, e\'cn on the cotyledons : these ova are 



