ee. 
’ TECHNICAL SERIES, No. 9. 
U. S. DEPARTMENT OF. AGRICULTURE, 
DIVISION OF ENTOMOLOGY. 
= 2 
THE LIFE-HISTORY 
OF 
TWO SPECIES OF PLANT-LICE 
INHABITING BOTH THE WITCH-HAZEL 
AND BIRCH. 
LPs 
THEO. PERGANDE, 
ASSISTANT ENTOMOLOGIST. 
PREPARED UNDER THE DIRECTION OF THE ENTOMOLOGIST. 
x WASHINGTON: 
ys GOVERNMENT PRINTING OFFICE. 
1901. 
