206 OHIO EXPERIMENT STATION: BULLETIN 194 



EXPLANATION OF PLATE III. 



Fig-. 1. The pine leaf scale", natural size, with the twice-stabbed lady 

 bird, Chilocorus bivulnerus Muls., feeding- upon the scales- 



Fig-. 2. AdiO.t females of the elm bark louse. 



Fip 3, The pine bark aphid upon the base of a pine,, 



