222 DIPTERA OR TRUE FLIES. 



all over the south, west, and in Yorkshire, &c. A second brood 

 is the exception here, the insect passing the winter in the flax- 

 seed stage, which remains very often, if the corn is not cut 

 close, in the "gratten." Numbers may also be seen in the 

 cavings and screenings from the threshing-machine. Wheat, 

 barley, and rye, as well as the wild grasses mentioned, are 

 attacked, but never oats. 



Pivveiifion and Reinedies. — In those areas where C destructor 

 is very abundant it is well to use the stouter-strawed varieties 

 of corn, and to burn the stubble after an attack by firing the 

 borders of the fields. All infested screening should be destroyed, 

 and light grain, which may often contain the flax-seeds as well, 

 given to stock. The Hessian fly is subject to a number of 

 Hymenopterous enemies. In 1888 Mr Enock bred from 1694 

 flax-seeds 58 more parasites than flies. 



The Wheat Midge (Diplosis teitici). 



The Wheat Midge is very prevalent in England, and causes 

 persistent loss in corn-growing districts. It is about the same 



size as the Hessian fly, 

 but more delicate in 

 structure, and yellow or 

 orange in colour, except 

 the eyes which are black. 

 It belongs to another 

 Fio. 120.— WiKo or DIPL0SI3. genus, Diplosis, whose 



characteristic wing ven- 

 ation is given in fig. 120. The female fly has quite a long 

 ovipositor, and may often be seen in the fields in clouds, flying 

 about low down amongst the stalks close to the ground in the 

 daytime, when disturbed, but at sunset they come up to the 

 ears to deposit their eggs in the florets of the wheat. The 

 liirvae are yellowish-red in colour, and feed off' the developing 

 grains, thus spoiling them. Numbers of larvfe are found in 

 each ear, and cause a disease generally spoken of as " red gum " 



