92 INSECTS WHICH PREY UPON AGRICULTURAL PLANTS. 



Society of England, recommends the ground to be dibbled full 

 of holes into which the grubs would fall, thus giving an oppor- 

 tunity to destroy them ; but it is not very easy to see how this 

 plan could be economically carried out on say a field of twenty 

 acres. The grubs can easily be found at any time in the spring 

 among the young braird at an inch or so below the surface. 

 They are thick and short, about one inch long, and of an earthy 

 colour. In a quick growing and mild spring the damage they 

 do is not so apparent, for the reason that if there is heat they 

 quickly develop and attain the full-fledged state, and the crop 

 is also better able to withstand their ravages. They delight in 

 moisture and can scarcely be drowned, and consequently we see 

 them swarming among grass in meadows — both fly and grub, a 

 sign that draining would act as a material check. This insect 

 will destroy the roots of almost any crop — grass, grain, or green 

 crop. 



Cecidomyia tritici (the British Wheat Midge). — A small 

 yellow gnat about one-fourth of an inch in length. It is pro- 

 vided with a very long slender retractile ovipositor, to enable it 

 to lay its eggs at the foot of the glumes of the wheat flowers in 

 contact with the germen. These when hatched produce minute 

 yellowish grubs, which feed on the pollen, and thus prevent the 

 fertilisation and consequent swelling or "filling''* of the grains. 

 They frequent many plants besides wheat,— couch grass 

 especially. The antenna of the imago under the microscope 

 resemble hairy beads remotely strung. The eyes are large, form- 

 ing the bulk of the head, and visible to the naked eye on account 

 of their black colour. The eggs are laid in June in the ear 

 whilst it is in flower, and the larvae live there until fully grown, 

 when they change to pupffi upon the sound grains and inner 

 valvules, or enter the earth to undergo their transformations ; 

 some of the flies hatching out during the same summer, and 

 others not until the following June. The only remedy which 

 can be applied is to clean the seed well, so as to get rid of the 

 adhering chrysalides. They fly in the evening between seven 

 and nine o'clock, and are easily distinguished by their bright 

 yellow colour. 



Cecidomyia mcice (the Vetcli Midge). — This insect is allied 

 to the preceding species. It attacks the flowering heads of the 

 vetch and other legumes. The affected heads grow distorted, 

 and on opening them out one finds little orange-coloured larvae, 

 which taper at the head and are blunt at the taii. They live 

 concealed in and amongst the calyces of the flowere, and entirely 

 consume the incipient pods. 



Cecidomyia destructor (the Hessian Fly). — This is a species of 

 wheat midge very common in America, where it is exceedingly 

 destructive to the wheat crops, some districts having k) give up 



