REPORT OF THE STATE ENTOMOLOGIST I912 87 



fair that more of such trees will die or parts of large limbs break 

 off in a year or two. Our attention was also called to several large 

 sugar maples now dead, which were marked as having been 

 sprayed the preceding year and had not been removed last year 

 because it w^as supposed that they had not been seriously affected 

 by the application. An examination of a number of representative 

 trees here and there only served to confirm our findings of the 

 preceding season and to exonerate injurious insects from direct 

 responsibility in the wholesale destruction of sugar maples. The 

 local character of the injury and the difficulty of attributing the 

 trouble to malnutrition, overcrowding or other general adverse 

 conditions is strongly illustrated by small to moderate sized hard 

 maples standing in front of numbers 125, 151 and 157 Cottage 

 avenue. The lower limbs of each of these trees had evidently died 

 the preceding year and had been removed, although the maples 

 stood in thrifty lawns some distance from the street and w^here 

 conditions were most favorable for a vigorous growth. 



After we had made examinations of the Mount \"ernon maples 

 and reached certain conclusions, we learned of similar injury fol- 

 lowing the application of a miscible oil a few years earlier to sugar 

 maples in the vicinity of Philadelphia. There were about 100 trees 

 sprayed, sugar maples and Norway maples alternately, and at 

 least 75 per cent of the former, we are informed, died soon after 

 the treatment. Those conversant with the conditions in this latter 

 case attribute the injury to the application of oil. 



The sensitiveness of the sugar maple to oil and the possibility 

 of the rapid death following treatment therewith, is evidenced by 

 a photograph taken by the late Professor Slingerland in July 1903 

 and kindly placed at our disposal by his successor, Prof. G. W. 

 Herrick. The photograph shows several dead sugar maples and 

 the original record is as follows: "Effect of kerosene bands on 

 maple trees. Maple trees treated with a band of kerosene in 1902 

 m front of fraternity house on Seneca street (W. H. Sage home). 

 Taken in July 1903. Trees practically dead." A band saturated 

 with kerosene is quite different from a trunk sprayed with petrol- 

 eum or miscible oil. Nevertheless it is possible to conceive of 

 conditions under which enough oil, either pure or as an emulsion, 

 might be left upon the trunk after the evaporation of water or 

 other emulsifying fluids and bring about a condition nearly identi- 

 cal with that produced by oil-saturated bands. 



The unfortunate developments on sugar maples, following the 



