172 OHIO EXPERIMENT STATION: BULLETIN 194 



It is an admitted fact that insects prefer 

 Avoid i>oor environment . , t , , . 



at planting time. the weaker to the stronger plant, and 



when we consider how much more easily 



a healthy, vigorous tree withstands insect attack than does its 

 weaker neighbor, it is self-evident that, if for no reason other than 

 the future control of insects, we should attempt to grow strong 

 trees. Much can be accomplished toward this end by not planting in 

 unfavorable immediate surroundings, such as over or near a gas 

 main, thus running the risk of having the tree poisoned by escaping 

 gas; nor directly under high-tension electric wires, the injurious 

 burning effects of which are well known; nor too near th'e street, 

 where the trunks are subject to injury; nor in soil deficient in 

 plant food; nor in a half dozen or more additional situations that 

 might be named. 



Tall growing species subject to insect ' 

 Plant to make tnsect , , . .. .. - , 



warfare possible. attack should not be P lan * ed . close beslde 

 buildings, thus making it impossible to 



spray them properly without covering the side of the building with 

 the spraying mixture. This is one of the great difficulties exper- 

 ienced by a city spraying department. Householders object ser- 

 iouslyand justly too to the disagreeable mixtures. To illustrate 

 the necessity for exercising this precaution take, for instance, the 

 applying of the lime-sulfur wash, a mixture used quite extensively 

 as a scale destroyer. This mixture when sprayed upon a painted 

 surface combines chemically with the paint, causing some shades 

 to discolon It is absolutely impossible to spray a tree located be- 

 side a building without some of the mixture being misplaced. 

 COMMONLY INJURIOUS SPECIES. 



It is the author's intention in his treatment of the individual 

 shade tree pests to deal with each species as briefly as possible, 

 but at the same time to afford a working knowledge for operations 

 against it. To this end the description of the various insects will 

 be confined to pointing out the characteristics most useful in dif- 

 ferentiation, and only such phases of their life histories will be 

 dwelt upon as bear directly upon our understanding of the methods 

 of control suggested. No attempt is made to list all of the insects 

 that may be found injuring ornamentals or forest plantings within 

 the borders of the state, but only those species are considered 

 which are at present doing damage or those that may likely be in- 

 troduced within the near future. For more complete information, 

 no better source may be found than Memoir 8, New York State 

 Museum, entitled "Insects Affecting Park and Woodland Trees" 

 by Dr. E. P. Felt. 



