CONTENTS 



Page. 



Introduction 7 



The genus Isosoma 9 



Dealing with the destructive species <nitside of the grain fields 11 



The greater wheat straw-worm (Isosonia grande Riley) 14 



Previous record of the insect 14 



Discovery of the summer form 15 



Discovery of dimorphism and alternation of generations 16 



Riley's name, Ixosoma tritici, invalid 17 



Life history 17 



Oviposition of the spring form (minutum) 18 



Oviposition of the summer form (grande) 19 



Description 21 



Adults of summer form ( Isosoma grande Riley) 21 



Larva, pupa, and egg of summer form 21 



Adults of spring form {Isosoma minutum ) 21 



Larva and pupa of spring form 21 



Natural enemies - 22 



Preventive and remedial measures 22 



Distri] )ution 23 



The joint worm ( Immnna tritici Fitch ) 23 



Previous record of the insect -' 24 



Life history 26 



Distribution 26 



Description 27 



Adult female , 27 



Adult male - 27 



Natural enemies 27 



Remedial and preventi ve measures - - 28 



Difficulty in recognizing the species - - - - 28 



The barley straw-worm ( Imaoina hordei Harris) 29 



Previous records of the insect 29 



Life history 31 



Effect of the larvie on the plant 31 



Description 32 



Adult female 32 



Adult male - - 32 



Natural enemies 33 



Preventive measures 33 



The captive Isosoma ( Isosoma captivum How. ) 34 



Description 34 



Adult female 34 



Adult male 35 



3 • 



