TECHNICAL SERIES, No. 9. 
USE roi WENT OF AGRICULTURE: 
DIVISION OF ENTOMOLOGY. 
THE LIFE HISTORY 
OF 
TWO SPECIES OF PLANT-LICE 
INHABITING BOTH THE WITCH-HAZEL 
AND BIRCH. 
BY 
THEO, PERGANDE, 
MSS St ANG “EIN Ow © LE ©O1Gls T- 
PREPARED UNDER THE DIRECTION OF THE ENTOMOLOGIST. 
WASHINGTON: 
GOVERNMENT PRINTING OFFICE, 
ROOae 
