33S 



AN ECONOMIC ENTOMOLOGY. 



certain grasses also sustain the species in the interval between 

 harvest and seeding. 



The injury is done by stunting and aborting the wheat plants 

 in the fall, and in dwarfing stalks in the spring or so weaken- 

 ing them that they fall or ' ' lodge' ' readily, preventing thereby 

 the development of the ' ' ear' ' or of the grain in it. 



Insecticide applications are hopeless, and modified farni practice 

 is the only satisfactory measure within our power. Very late sow- 

 ing in the fall — as late as it is safe to do so — will force the insects to 

 oviposit in volunteer shoots or grasses, and the later germinating 

 crop remains exempt. As far as possible, infested stubble should 

 be ploughed under deeply immediately after harvest to destroy a 

 large percentage of the "flaxseeds," or it should be burnt. 



Another, related pest, is the "wheat-midge," Diplosis tritici, 

 which in the larval stage feeds upon the kernel of the grain, 

 dwarfing it or causing its entire abortion. This larva is quite 

 red in color, and the parent midges are about in June, oviposit- 

 ing in the blossoms or on very young kernels. In this case 

 also deep ploughing after harvest is advisable, and after threshing 

 all chaff should be disposed of so as to destroy all chance of life 

 for such insects as may yet be in it. 



The "clover-seed-midge," Cecidomyia leguminicola, is also a 

 dangerous enemy in some localities where seed rather than hay 

 or fodder is desired. The midges lay their eggs in the flowers, 

 and the resulting larvae feed upon the forming seed, utterly de- 

 stroying it. Where the insects are known to occur, cutting an 

 early crop just when it is in full head and depending upon a sec- 

 ond crop for seed is good practice. The midges oviposit in the 

 flowers of the first crop, and those of later date will be practically 

 exempt. The cutting can be high, so as just to include all the 

 heads, which will be rapidly renewed from the vigorous stalks 

 remaining. Fall ploughing infested fields is good practice, or 

 ploughing under after cutting, and planting some cultivated crop 

 that involves frequent stirring of the soil. The insects winter 

 just below the surface among the roots, and the practice above 

 suggested looks towards winter killing them. A liberal use of 

 lime and kainit after the crop is off" is also good practice, and 

 will kill many of the larvse then barely beneath the surface and 

 not yet in their cocoons. 



