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OHIO EXPERIMENT STATION: BULLETIN 332 



PLATE LVIII 



Fig. 1. The Pine Bark Aphid (Chermes pinicorticis) . The trunk of a 

 young white pine showing heavy infestation by this insect. The white, floccu- 

 lent, waxy covering which the lice secrete from their bodies renders their 

 presence very noticeable. 



Fig. 2. The Cockscomb Gall of the Elm (Colopha ulmicola). These galls 

 both in form and color, particularly when the leaf is green and the galls are 

 growing, very closely resemble the comb of a cock. This figure is reduced in 

 size. 



