MISCELLANEOUS PAPERS. 



INSECTS INJURIOUS TO GRAIN CROPS, 

 BY R. H. PETTIT. AGRICULTURAL COLLEGE. 



Iii order to comprehend the changes that occur among insects and the 

 terms used in describing them, it will be necessary to remember that 

 the majority of insects normally pass through four stages, viz. the egg, 

 larva or grub, pupa or cocoon, and adult. The injury to crops is usually 

 done by the larvae and adult insects, but in fighting them it is often found 

 that a species of insect is most easily destroyed in one of the other stages, 

 as in the pupa or egg stages. So it is with the Hessian fly. This insect 

 is most easily destroyed in the pupal stage, which corresponds to that 

 of the cocoon in some insects. The life-history of the Hessian fly is 

 briefly as follows: The adult fly appears about the first of September to 

 lay the eggs on young sprouting wheat; they continue to fly until after 

 the middle of the month. The eggs are laid on the upper side of the leaf 

 and the young go down inside the sheath to about the level of the soil. 

 Here they thrive on the succulent stem until ready to turn into the flax- 

 seed or pupal stage, which they do late in the fall. The flax-seed stage de- 

 rives its name from the resemblance of the pupae to flax-seed both in form 

 and in color. These little flax-seeds remain in the young wheat till spring, 

 when they crack open and each live pupa or flax-seed gives forth a small 

 delicate fly that is at once ready to deposit more eggs. The eggs de- 

 posited by the spring brood hatch the same and the larvae behave the 

 same as those of the fall brood until the flax-seed stage is reached and 

 this flax-seed or pupa resembles that of the fall brood except that it is 

 placed almost invariably above the first joint of the wheat stem between 

 the true stalk and the sheath. Here it remains until after hardest, when 

 the fly comes out to lay another crop of eggs. 



As has been stated, the pupa of the second brood is placed just above 

 the first joint. Now the presence of the flax-seed so weakens the stem 

 that it easily lodges, bending over just above the insects. This Is often 

 the first intimation to the farmer that anything is wrong. Whenever 

 such lodged wheat is seen to be common, it should be carefully examined, 

 and if the flax-seeds are found, the stubble should be burned immedi- 

 ately after harvesting if possible, or else the ground should be immedi- 

 ately plowed. If we wait for a few weeks, then the fly will come out and 

 no amount of plowing will do any good. 



Other remedies are, the rotation of crops; trap-crops; late sowing of 



