202 OHIO EXPERIMENT STATION: BULLETIN l 



EXPLANATION OF PLATE I. 



Fig-. 1. The oyster shell bark louse much enlarged. 



Fig-. 2. The oyster shell bark louse enlarged two diameters. 



Fig-. 3. Branch of horse chestnut defoliated by oyster shell bark louse. 



Fig. 4. Scurfy bark louse much enlarged. 



Fig. 5. Scurfy bark louse, enlarged two diameters. 



