REPORT OF THE SOCIETY 105 



Hessian Fly. 



This insect periodically occasions great losses to wheat, rye and barley. 

 In fall wheat regions there are two generations each year. The adult insect 

 is a small, dusky, two-winged fly about half the size of a mosquito. The eggs 

 are laid on the upper surface of the leaves, in the case of the fall brood the 

 second week in May, and in the case of the spring brood about the first week 

 in September in Ontario. The maggots on hatching move down the leaf 

 and soon imbed themselves at the joints of the stem near the ground and 

 injure the plants, often completely killing them. They appear as brown, oval 

 objects, resembling "flax-seeds," and it is in the flax-seed condition that 

 they winter. 



The best preventive measures are (a) late sowing, (b) thorough pre- 

 paration of the land; (c) trap crops; (d) burning or plowdng under infested 

 stubble when practicable; (f) co-operation among the farmers. Sow as late 

 as local conditions will permit, in a good seed bed, and get the neighbors to 

 do the same. 



The wheat joint worm {Isosoma tritici)—Ad\x\X. fly, much enlarged. (Reduced from Howard). 



Joint Worms. 



Two species of Joint Worms damage wheat — one producing knots or 

 swellings on the stems, single brooded and confined chiefly to the East; the 

 other chiefly in the West, double-brooded and producing but slight swellings 

 on the stems. Both species are often very injurious, especially to spring 

 wheat. The adults are minute four-winged flies. 



The best control measures are (a) rotation of crops; (b) burning and 

 plowing under of stubble when practicable, or harrowing stubble in the 

 spring and collecting with horse-rake and burning; (c) preparation of good 

 seed bed. 



