BULLETIN 154.J [FEBRUARY, 1907 



Ontario Department of Agriculture. 



ONTARIO AGRICULTURAL COLLEGE. 

 INSECTICIDES AND FUNGICIDES. 



By R. Harcourt, Professor of Chemistry, 



and H. L. Fulmer, Demonstrator in Chemistry. 



OBJECT. 



Year by year the damage done to the crops of the farm, orchard, 

 and garden by insects and fungous pests seems to be increasing. Some 

 cf these pests may be a blessing in disguise, in that the remedies used 

 for their eradication have been beneficial in other respects ; but, in order 

 that they may be successfully combatted, it is essential that the farmer 

 know how to fight them to the best advantage, and that he have a clear 

 idea of the nature of the remedies employed and the precautions that must 

 be observed in their use. The literature on the subject is voluminous, 

 but it is scattered and not always accessible to those who require it. In 

 this bulletin an attempt has been made to gather the information obtain- 

 able on the subject into one publication and present it in a manner that 

 will be helpful, in the hope that it will fill a long felt want. 



INTRODUCTION. 



To spray with any degree of success requires, besides a knowedge 

 of the acting principle of the remedy which is being employed, a rather 

 intimate acquaintance with the enemy which is being combatted. The 

 different classes of insects and fungous diseases do not show similar 

 characteristics. If it were so, then the question of remedy would resolve 

 itself into a very simple one ; the discovery of a single successful one 

 would end our labors. As it is, a great many of these remedial com- 

 pounds are required in plant economy, the absolute number needed de- 

 pending entirely upon the different ways in which insects and fungous 

 diseases attack their food or host plants. This results largely from dif- 

 ferences in anatomical and physiological structure of these little but often 

 highly destructive animals and plants. 



Classes of Insects. 



Practically all insects can be divided into two leading groups : (a) 

 those which actually chew and swallow their food and have what the 

 entomologist calls biting mouth parts, and those which obtain their food 



